Morphology of Cicadidae

THE MORPHOLOGY OF THE CICADIDB. 365

19. The Morphologr of the Cicadidx (Homoptera). By J. G MYERS, Sc.D.", Imperial Bureau of Entomology, late 1851 Science Exhibition Scholar.

[Received March 20,1928 : Read April 17, 1928.1

(Text-fi gnres 1-7 5 .)

CONTEXTS. Page

Introduction ........................................................ 36t5 (1) ICxternal Anatomy ............................................ 365

a. General Characters ............ 365 b. Integument and Coloration .............................. 366 c. Head and i ts Appendages. d. Thorax and i ts Bypendages .............................. 380 e . Abdomen and i ts Appendages ........................... 402

a. Wervous System and Sense-Organs .................... 414 L. Bluccular System .......................................... 426 c . ltespiratory System ....................... d. Alimentary System ....................................... 433 e. Circulatory System _ _ . . _ _ . _ _ ,f. Fat-Body ..................................................... 456

.............

(2) Internal Anatomy ................................. 413

g. I<eproductire System .................................... 456 (3) Sound-Organs ... 469 .........

a. Description of Sound-Organs .......................... 460 71. Historical Reriem .......................................... 467 c . Accessory stridulating apparatus of Tettigacli xe... 472

IXTRODUCTIOS. I n spite of their si/;e and the interest which their loiid."song

1 1 % ~ excited in Man from the earliest times, the Cicadas [have been extraordinarily neglected by morphologists. The sound- producing apparatus has been the snhject of considerable study and much controversy, hnt the rest of their structure has remained almost unknown or greatly misunderstood. The following study ~vas made largely in the Entomological Labora- t,ory of the Rnssey Institution, HRrvarcl University, and I am deeply indebted to Professor W. M. Wheeler and to Professor C. T. Brues for help and advice of every kind dnring its course.

(1) EXTERNAL ANATOMY. a. GENERAL CHARACTERS.

Tile Cicatlas are among the largest insects included not only in Their shape, with the

25

Homoptera but in the whole Order. * Communicate:l by S. A. NEATE, M.A., D.Sc., F.Z.S.

PROC. ZOOL. S 0 ~ . - 1 9 2 8 , NO. XXV.

366 DR. J. G . JIYERS ON TIIE

I)otiy usunlly short and 5tollt il.11tl tlie wings long or iiioderately so, is rentleretl chracter is t ic by the normally short but wide head, with proiniiient eyes and conspicuous ocelli, freqnently red in cvlour, n.iid arr:iiiged in a triangle upon t h e crown. The head may be pro(lriced, bnt iiever to sucli an extent as i n t h e FLilgoridz- tlie oiily other Honioptera newly rivalling tlie larger cicadas in

The fore-legs siiom gre;it swollen spinose feinorn, while t h e wings, tliorigli strong, are usnally tr:tnsparent, but in some cases opaqiie ~ n d lriglily coloarerl. The venation is compai,atirely pyiuiit.ire ant1 siinple, with, i n addition, a n auibient vein cuti,iiig off' a f:iirly wide border.

'I'lie irirtles of all sa.ve one genus posses5 :t coinp1ic;tted sourid- organ in the 1st itbtlornin:Ll segment, wliile both sexes

ied wit,h t h e most complex chortlotona.1 oigan known, lio~~setl i i i :t swelling on e:icIi side of tlie 2nd ~bc1oinin:ri segment.

AAil the species are piirely pliytophagons, l i \ i n g on tlre sap of pl:ints. The iiyrnplis tlirougllout the fitlnily are snbterriiiiean :tiit1 rioted for. t h e extreme length of the cycle-in one well- c:st,:il)lisheil case leaching seventeen years. Their for,e-legs are liiollified i i i a. c1iar:tcteristic may for fossori:il purposes.

'Ciie eggs are tleposited in t h e stenis of pl:i.iits by means of t h e lx~werful ovipositor carried hy the fernale. The young nymphs 0 1 1 1i:Ltching out, drop a t oiice t,o tlie grountl ancl burrow.

'Vhe :ttiiilts are comparn,tively short-!ived, enclnring at most one ae;\ .on. '['lie song exhibits gi.e:it, coristnnt specific vai.intion n.nd ;1ppreiitly p1aj-s a. par t i n the mating preliininnries.

S17.6.

h. INTEGUMENT AXD COLORATIOX. The

ciit,icie 1iin.y be ra.rely entirely smooth or covered with pul~escence or pilosit?'. ' h e 1)ubescence is of ten fine, close, :ind continuous, :ii11] n~:r,y conipletely obscure the colour beneath. Hi1vei.y or gold ll,:i,rIiiiigs foriiietl by p t c l i e s of pubescence w e f i q u e i i t . Pi,tiinosity is less fi ,equent than in Fiilgoroit1e:i 01- Mternorri.iyrlcli;~. Lt, is ~rsnally confined t o t h e iiiiriiediilte neigliboui.lioo~-ooften a 1liei.e riiii--of t h e iiioi'e posterior :ibdoniinal spiracles, biit may OccIIr in p tc l ies elsewliere. Nerertlieless, wnxy inater id 1ma.y exist n.s i t11 extremely tjliiii and pra,ctically imperceptible covering < ) ~ t ? y the wliole of tlie body-snrface, a.s Fumouze (1888 c) * fouriti ill 7'ibicen ~7lebr ia and J17wchTy.s smzguinecc by t h e \ise of cl-ieinical ~ ~ ~ ~ t l i o ( l s . Pilosity is aasoci:ited chiefly wit11 altitnrle. Anlong tllose X e i r Zealant1 species of ilfelnwpwltu wliieli eri joy ;I, con- SiiIeyitbIe i.xlige in altitiidinal distribution, there is a clear correlntiou hetween elevation nncl hairiness. Alpine or subnlpirle species, ho~vever, are rmrrly a.1wa.y~ more hairy t h a n closely- i&ted Iowland forms. Tettigarcta crinita Dist., perhaps the lil& ~,rofiisely hairy of linowri cicadas, occurs on &It. Kosciiislto itt :LII elevation of 5000 €eet (H. Ashton, in Zitt.).

'rile iritegiinient of cicadas is generdly well-cliitinized.

l lOlt I ’HOLOGT O F TKIE CICADID23. 367

I he colour-pattern of Cica.clas contains usually two elements- an arrangement of (lark coticnlar iiiarkings on ft paler hypo- tlernia.1 ground-colour. Sonietimes one will predominate ; sometimes the other.

Net,allic colours would seem to be zbsent, but, a re occasionally simula.ted by pubescerice.

An interesting study of t h e pigmentntion i n Jfugicicarlu septeir- t l ec im lias been iiiade by Gortner (191 1) *. H e remarks t h a t t h e rapid clinnge froin t h e pale-coloured, almost cre:urry, iiynipli t o Lhe deep black arlult ‘‘ presents one of the most reiiiarka.ble ctinriges i i i colonxtion ” of which lie is amw’e. From his earlier work on tlre pigmentation of t h e iiieal-worm (Il‘eiteb~io n a o l i t o ~ ) h e h; td expected t o find t h a t th i s c h m g e i n colour wns a n oxitla.tion, induced by t h e action of a.ti oxidizing enzyme, aiiil his expectation was fully realized, altliougli he fouiirl iiriportant tli fferences.

The colour ‘‘ is due t o t h e action of n tyrosinase act ing 011 some aromatic amino phenol, poilucing, as a i.esnlt of tile action, n hlnck, insoluble pipnieut. Tliat it3 is an oxitlatiori is shown in tJie following n-nys” (Gwtner , 1911) :-

I . If an i m a y jnst, emerged be placed in mnter no colomtion :ippeni.s ; yet if i t i s reiriovrd :it) an; t ime before decomposition sets in, t i l e coloration proceeds a t once.

2. If nn iinago just emeiged be kept i n a s t ream of CO, no

1 iiere was no difference i n tlie intensity or rapidity of coioratiori in insects kept duriiig, :&lid after. ecdysis i n sti,ong 1 iglrt, dim liglit, total tlitrkness, o r light filterecl tlirougli blue

On 1). 9 3 Gortner makes tlie iiitorestitig suggestion, inasmncli

‘‘ tliat t h e eiitire new cnt icnh is forriietl by t h e reaction i)etween t h e oxida+e aiitl the chimiogen, in the s:biiie manner tihiit tlre J:tpnese l:~,cquer is formet1 by t h e actJion of laccase on tlre milky 1:ihex of the h e I<hu.s w*i/,icifemc.”

r 1

s ; but if i n 0, t h e blackening proceeds norinally. I ,

g 1 R ss .

:IS t h e color,ation is a uniform black over the elitire surface,-

, I J.Ire \viiigs are nsnally colourless, bu t in some c:ises opaque aiid i)riiliiintly colonre~l. Gr:ifin von Iincleii (1 901) 11:ts studied t h e vYirig-iiiarlririgs, especi:i.lly i n some of tlie l’Zat!jpleura spp., which sliom spots :*nd stmxlrs. She finds the m;Lrkings :ire always (Ieterminctl i n position eitber hy tlre position of tlie veiris tlieni- sel\7es or of the rriiiiiite cross-foltls whicli may be seen i n certain li,vIlts in every cic:idii, tegmen and which she believes to be relics of :L close net-veining. The strongest markings a r e determined j i i position by tlie few cross-veins whicli rein:rin in tlie iiiiago. Eve11 i n tire niost trarisparetit tegmina there a re frequently dark

* 1?~11 refereiiccs are given in a comprehensive bibliography of the fami l r now I,t:ing publi.;lied by Meswu. George Routledge & Sons, Ltd. in my book &I the I3iology of Cicadas.

25*

368 DH. J. G . MYERS ON T H E

marks on the cross-veins or a.t the end-points of long veins. Uiedernimn (1914, pp. 1719-1721) discusses the Grafin’s results.

It is unfortunate tha t the only two cicada species on which tlie chemists littve worked were, from the pigmentation stand- point, highly anomalous. FLiinouze studied tlie red iiieclicinal Cicada, Ht~echys sccngziinecc, of the Orient. This species is colorired a striking red and black, ant1 possesses in addition a n unpleasant smell, and thus belongs to the forms coinuiomly regarded as protected by “ warning coloration.” Fumoiize (1888 b) isolated from i t n red pigment-“ rouge cl’Hueclijs ”- which gires the colour to the abdomen, ant1 a yellow hygroinetric sribstance.

c . HEAD AND ITS APPEKDAGES. The literature on the head :md its appendages is almost

entirely modern. After :L few references i n c!nssical antiquity w e find n o more itttention pait1 to this part of the cicada anatoniy until comparatively recent times. The early post-Renaissance observers were interested chiefly in the sound-organs and worked bat little on other parts of the cicada body.

Nevertheless, it worild be a mistake to suppose that Aristotle missed anything which could be seen, if not exactly perceived, by the iiieans at liis cornrnand. He believed that cicadas lacked a. inouth, or rather that the iiiouth and tongue were uriitecl so as to form a single part, through which, as througli :t root, the flnitls on which they live are sucked up (de part. Animal. lib. iv. 5). .\Ve s l d l return to this conception when discussing feeding- 1i;tbits. The Egyptians a.lso sw.w the rostrum or “ ncnleus,” aiirl interpreted i t a,s tlie plectruni of the nirisical instrument (Hora-- mi lo, V:ileriano Holeani). Pliny (lib. ii. cap. 37) quoted Xigidins to tlre eIfect that cicadas lack eyes-a st.atenient which is repeated by Monfet (1634),-and is perhaps based on the lack of the waiiness iisnal to cicadas a.nd other insects in tlie coininon Enrope:rn species, l’ibiceii, plebeicc.

!l.’l~e modern references will not be discussed in det,n.il nntil we 1 1 : ~ ~ tlexcribccl tlle part’s concernetl. I t will tlieri he easier to correlate tJie results of previous work.

I n h t e r clays some of t,lie most coiitrovertecl qnestions in ext,ernnI insect ariixtoniy have concerned the interpreta.tion of Hernipteroua Jiea,d-strncture. Some member of the family Cica -

d i t h has very often been tlie type studied, as in tlie case of Smith wit11 his startling lioinologies iri 1892, Marlnt,t, (1895), Meek (1903), and Muir and Kershaw (1911 u, 1911 b, 1912). .Writers on other families of Honioptera have often orientnted tliernseives on the large Cicaclidx; thus Funlrhoiiser (1917) ant1 Doering r lc22) . The literature is therefore biilky, hut,, in addition, t h e f:tct that Elemipteroiis head-structure is remarkably iiiiiforni througliout both suborders, brings in a s exp1anator~- of cicnda conditions interpreta.tions based on other forms: arid :dcls to the list such classical contributions as those of Geise

UORPIIOLOGP O F THE CICADIDB. 369

(1583), .Wedcle (1885): and the more recent work of Bagnion and PopoE(1911), and Tower (1914). Tlius it might reasonably be expected that the homologies of the trophi and sclerites have been clearly denionstratecl. But this is very far from the case. Moreover, as at least two other contributions (Metcalf, Hussey) on the subject in America alone are now either in the press or in manuscript, the present writer feels tha t no finality for the interpretation here supported can be expected.

I n a siibject so much discussed it is, of course, obvious that the structures themselves have now become moderately well known and the discovery of strikingly new morphological evidence correspondingly unlikely. Until the homologies of the Hemi- pterous nioutli have been finally elucidated by wider and inore comparative embryological studies of this and of all related orders, coupled with an advance in our knowledge of insect morphology in general, with clearer conceptions of the relationships and origin of the head sclerites in the most primitive inandibulate forins, finality cannot be expected in the interpretation of cicada head-structure. I n the following p a p I have therefore, after i ~ n examination of a11 previously published views and a study of both nymphs and adult cicadas, chiefly of New Zealand species of ~llelan~psulta, especially 111. ciiigulata and X . leptomera, attempted first a simple description of the head and mouth-parts, and then a collation of the arguments for and against the various divergent views, the snbsta.ntiation of mliich must lie sub jzbdice at l+mt until the publication of studies now in the press. For the adult condition, as Snodgrass has suggested, it is advanta.geous to study a soft freshly-emerged example, or even one extracted from the nymphal cuticle just before ecdysis.

Since tlie chief controversy concerns the homologies firstly of the two pairs of mouth-set% and secondly of the facial sclerites, the description of tliese will be made especially detailed. Unless otherwise stated tlie particulars concern ,I!felanzpsa,lta leptonzei-a a,clult, of which a head cleaned by Nematode worms more neatly t h n by K O H was fortunately available.

a. Descri$tion. of Head c d Xouth-parts. Viewed froni the front, the most striking feature is the large,

swollen, transversely-striated frons (text-fig. 1, J;..), of which the striations correspond with the insertions of the great dilator muscles of the sucking-pump. The upper edge of this sclerite p8sses into the cro\j-n or vertex*, from which i t appears to be separated by a transverse foltl rather than by a distinct suture. En the nymph at the final ecdysis the split does not occur along this fold but more cauda.lly, along two sides of a. wide tria.ngle of which tlie fold in question forins the base. This triangular

* Following C. F. Baker, we may regard crown as a less committal term than I n the Fulgoroids, moreover, the expressioiis are certainly not synonymous, osrtex.

since the vertex invades the region commonly knomn as front in these insects.

370 DR. J. G . MYERS ON THE

piece, which bears the median ocelliis in tlie adult, is apparently rather a part of the t ine frons tlixii of the true vertex. There sceriis no ieason against considering tlie sizes of the triangle a s the arms of the epicranial suture (text-fig. 2, es . ) . Theie is a fairly tlistirict liiie along t h e arms of tlie Y in the atlnlt head as vien erl internally (testJ-fig. 2). The rorrespoiirliiig sclerite in Membracidz, as shown by Hniel Brarich *. may also be considered the frons. In her figure the rpicmnial sutiire is clearly marked, and its arms are ‘‘ formed by the 1:iter:tl edges of the clypeus,”

she incorrectly Iiomologises t h e plate in qiiestion. Posteiiorly the cron n passas into tlie occiput wjthout furtlirr

Text-figure 1.

?C

Dfelampsaltn leptomem Myers. Face. f?., f r o n t ; c., clypens; Z., labrum-epipliaryiis; fs., frontal suture; gs., geiial suture; fp., frontal pit ; oc., rnediaii ocellus; mp., maxillary plate; Zr., loruni.

sutures. The paired ocelli are on the vertex just behind the arms of t h e I-. The conipoontl eyes are large and protruding. Tlie aiitennte comprise, as in all other hncl-ieriorrliynclla, a shaft or peduncle and a whip or flagellum. Tlie peduncle has two segmentg, the fii.st hidden by the horizontal antenna1 shelf, both simple, lacking sense-organs, a.nd considerably thicker tlian the first segment of the flagellum. The number of segments of the latter varies within close limits, bu t in Jfelnnzpsalta leptomercc is six. These taper to the apex, though in Nagicicada septelz- decina especially the apical one in a fresh conditlion may be somewhat swollen. Hansen (1890) gives five flagellar segments as normal t o the fnmily, bnt this is an error. Tlie sensillz, t o be described in a later chapter, a.re confined to tlie flagellum.

Bull. xviii. pl. 11. fig. 36, p. 86 ( E 7 ~ g l i a ) . * “ Morpliology and Biology of the Meinbracidz of Iiansas,” iians. linir. Sc.

MORPIiOLOGY O F TJ3E CICADIUB. 371

The lower margin of the frons passes into the clypeus (text- fig. 1, c. & text-fig. 6, c.), wit11 well-defined demarcation from tlmt sclerite. The clypeiis is considerably flat,ter, with a, more or less membranous structure wising froni its inner surface and projecting as a narrow groo\7ecl flap beyond its trunca.te apex. This structure--the lnbrurii-epiphar~nx (text-figs. 1 & 2, I.)-is throughout grooved on its inner sutrfa.ce for the reception of t he mandibular and maxillary set%, wliich lie basally between it and the closely-nppressed groove of the Iiypoplrarynx (text-fig. 2, JL). . The distal portion of the labium-epipharyx protects the set= at the base of the labium, where the dorsal trough of the intter is: shallowest.

MeZnmpsaZta Zeptomera. Occipital view of head, I<OI'I prepariition, trophi removed. bt., body o f , tentorium ; es., epicrailid suture : d t , dorsal arm of tentorium ;

ga., genal apodeme; fa., frontal ayodeme; h., hypopharyns; fp., frontal plate ; ~ r . , lorum (maxillary plates removed) ; Z., labrum-spipharyns ; oc.,

median ocellus.

On each side of frons and clypeus is a crescentic lorum occupying most of the true genal area in cicada (text-fig. 1, I t - . ) .

Lateral to this in tu rn is a Ionger plate, which i t largely hides from facial view. This is the maxillatry plate (text-fig. 1. nap.), which apically meets the free extremity of its fellow t o form with it ant1 the labrum a narrow pore through which the set= pass into the rostra1 furrow.

Retweeri lorum and frons is the frontal suture (text-fig. 1, fs.), which passes up to the crown. Separatir~g lorum from maxi!laq- plate is the genai suture (gs.), which almost joins the frontal suture posteriorly.

The sutures mark the external lines of deep flange-like apodemes (text-fig. 4, n) , t he first clear interpretation of which


Text-figure 3.

Xelairqmzlta leptomera. As test-fig. 2, but trophi in place.

YM., retractor of mandible ; am., articulation of mandible; ms., maxillary plate; m., mandible; mx., maxillary seta; t., teiidon of Meek ; ma., maxillary apodeme.

Text-figure 4.

MeZampsaZta cingulata (Fabr.). Exuvial head of ultimate nymph. a, , frontal apodeme; fp., frontal plate; fr., front; c., clypeus; t., tendons of

pharynx dilator muscles.

has been given by Muir (1926). The frontal apodeme is narrow near the antenna, but widens apically till it reaches the junction of the frons and clypeus, where it forms a strong s t ru t at a point

NORPHOLOGY OF THE CIDADIDB. 373

iiiarked on each side of the face by a deep pit. Surely t>liese pits (text-fig. l,f?.), situated exactly at the junction of the plates we :),re calliiig Jyons and cbypeus, are homologous with the frontal pits of the cockroiZch and other orthopteroids, and, as such, good landmarks for the recognition of these two sclerites. They may be taken as additional grounds for Mnir’s supposition that the struts in que.stion are homologous with the anterior arms of the tentoriuni. These struts flatten out and join in tlie middle line to form the posterior portion of a deep, trough-like, strongly-chitinized structure which all previous workers before Muir (1926) appear t o have regarded a.s the floor of the pharynx, for which, however, it is only the support, since Muir fonnd in a nymph just a?.fter ecdysis tha t the pharynx can be separated complet~ely as a membranous tube lying on t’he floor of this trough (text-fig. 4: fp.). I have been una,ble to nchieoe this separation myself in nymphs or adults, but I had nolie near ecdysis. This boat-shaped trough is then in i ts relationship strikingly similar to the fronta.1 plate of tlie tentoriuni in some ortliopteroids, and shoiild certainly be regarded a s liomologous therewith.

The genal suture forins inteim~lly a similar apodeme, the .anterior portion of wliich joins i ts fello~v from the opposite side to form a.n anterior support for the ventral wa.11 of the pharynx.

The dorsal a.rm of tli e ten tori II m -n ea rl y always hi t b ert o (Snodgrass ; Muir and Kerdiaw, 19 11 ; Doering, Funkhouser) considered t,he anterior-ariPes froin (Muir sa,ys ?rear> this gem1 apodenie just at i ts approximation to the frontal apodeme and near the base of the antenna (text-fig. 2, dt. & text-fig. 3 ) . It joins the body of the tentorium near the niiddle. This latter is a short transverse rod, conspicuous in occipital view, swollen near each end a t the junction with the dorsal arms, and a.t t~clied to the apices of the maxillary aporlemes. Thence t h e tentorial body is connected to the outer wa.ll of the liea,d-capsnle by an invagination at the ill-defined !abial suture of Muir (1926), this inva,gination possibly corresponding with the posterior arm of the tentoriuin.

“ A t the base of the free apical portion of the maxillary plate on the unclei~sic\e is the opening of tlie deep invagination which forms the large maxillary apodeine.“

The genal apodeme joins it, and the two form a pouch in which lie the mandibular and maxillary set=.

The mandible is representecl solely by a long stout seta (text- fig. 3 , nz.) of the outer pair and its fairly simple bnse. This base consists essentia.lly of a niodera.tely wide plate “ bent over a t the top,” to use Snodgrass’s (1921 a ) expression, a,nd connected with tlie ~vvxll of the head-capsule near the upper corner of the frons and the origin of the dorsal a.rm of the tentorium. Un this plate a re inserted the protractor niiiscles, which are attached to the lower portion of the face, chiefly of the lora. The retractor

Smith (J. B., 1892) regards i t as the nientuni!

(Muir.)

374 . DR. J. G. MYERS ON Tf lC

mriscles are iiisertetl at the bulbons portion of the mandible where the seta passes into t,he wide plate, and are attached to tlie crown behind the ocelli. The innndibular set= are barbed at tlie tip, a i d together loooely enclo\e the tightly-conjoined niit xillary setw within the roPt,rum.

The maxilla base is cnrrietl further back into the head-capsule th.m that of the mandible. The protractors attach chiefly t o the loner part of the maxillary plate, while the retractors go t o the vertex near the attachment of the in,cndibnldr ones. The m:Lxillai-y setre are fitier and intimately lockell together, forming a water-tight tube which is split with difticultp and has often been described (e . g. Buckton) as one piece, and which lies in the looie channel between the apposed mandibles.

The maxillary set= are connecteil by tongues to form this tube, R S seen in cross-section (text-fig. 6 ) in l+icZicina. The central tnbe is bounded on a11 sitles by the inner walls of the maxillary set% (fc.), but the section shows there are three holes enclosed in

Text-figure 5.

s

B’idicina semilata (Wk.). Cross-section of maxillary tube. .fc., food-canal ; s., salivary canal ; Z., lumeii of one maxillary seta.

the walls of the canal thus formed. Two-one placed excen- trically in each seta--are small, and are the lumina of these organs, allowing passage of nerves and tracheE, which stand out as fine Iiairs wlien tlie maxi1l:try setw are cut. The third passage is hrger, and is formed by a deep nenrlv enclosed groove i n one <eta roofer1 over by the apposition of its fellow. Tlie large central canal IS, of course, for the passage of footl, and the pnrietsl channel for that of saliva. I n Graphosonza, and npp:rrently in most other I-leteroptera, tlie two canals are more nearly elqnal, the salivary passage being slightly smaller.

Tlie set= are capable of considerable extension beyond the t ip of the labium (text-fig. 68).

Tlie Irypopharynx is a pad-like triangular structure grooved for the reception of the set= and fitting closely against the inner surface of the epipharynx. Below the terminal portioii of the hypoylrarynx is a swelling coctaining the salivary pump, tlescmberl more fully in the account of the alirrientary system.

MORPHOLOGY OF THE CIDGDIUE. 37 5

TIiis terminal par t is fiised with t h e cliitinous plate supporting tlie ventral mall of t h e pharynx. Tlie latela1 wing5 of t h e hypo- pliarynx seem t o be tlilectly cont inuor~s with tlle lora, a s rioted by Snotlgrass (1921 a ) arid seen ill text-fig. 2 (h., Z/*.)-an extremely ariom:iIoiis conrlition. Possibly t h e term h?JpOp1LcC12/1~~ is t o he restricted t o tlie ternlirlal somewhat spoon-sliapecl portion, as held by Muir and Kerslraw (1911 a, p. 5 ) .

I t i s

attaclietl by feebly-chitiriizecl membrane, xiid, a s noted by hleek. showi 5trongei. connections m it11 t h e prothorax tban wit>h tlie liead-a condition (leveloping early i n emblyonic life (Hepnions, 1899). In i ts distal portion t h e labium is a tleep, t r o u g h - l i k almost closed tube. Three segments are recogliiznble wit,ll s i p s of IL fourth ( text fig. 6). From t h e proxilnal segment t h e cliititiized floor of tlie labial groove becodhes diffeerentintetl 3s a free chitinizetl roc1 (text-fig 6, v.) f o r t h e inseltion of t h e muscles of t h e labium.

Uugnion and Popoff say t h a t i n t h e Pentatomoitl, G~apho,~ol,,a

The lnbiuin forms t h e rostrum 01- sheath for tlie set=.

Text-figure 6.

\ ,c

JfeIampsalta Isptomera. Rostrum of iiltirnate nymph. c. , clypeiis ; I., labruni-epiphar).ni; gm., gular meiiibraiie ; v., cliitiiiized rod.

lixeatuna (1911, p. 651), t h e labial canal forms, near the t i p at least, a completely closed tube. Above th i s (proximally) t h e groove is open to permit t h e labium to bend away from t h e set= and nllovc. penetration, t h e flexion occurring between t h e first and second labial segments. They nate tha t , if t h e set= by accident a re drawn riitirely out of tlie labial trough so as t o escape from t h e closed apical tubular part, t h e bug is nilable t o re turn them :mrl dies of starvation. W e doubt whether this condition is at a11 general, and we have shown i n t h e New Zealand Pentatomid, Rhopulinzorpha, t h a t when t h e set= a r e penetrating t o tkie fullest extent, t h e labium is witbdrawn from them completely and foldetl back along tlie venter *.

I n cicndns, at least in 111. cinpdatcc, t h e apical portion of the labial gioove is not shut . The shortening of t h e labium t o allow penetration of tlie set= takes place by wrinkling transversely in t h e terminal segments.

’* “ The Feeding-habits of Hemiptera,” New Zealand Jourri. Sci. R: Tecliii- iv. pp. 266-266, figs. 1-3 (1921).

376 DH. J. G. MYERS ON THE

'l!lre mechanism of t,he mouth-parts is so linked up with the fnnctioning of the sa.livary glands and pharynx tha t it has been d e d t with under the physiology of the digestive system. The .chief point t o emphasize is the presence of a distinct salivary canal in the wall, a,s it mere, of the much larger food-cha,nnel. This 21:~s been frequently overlooked (e. g. Snodgrass, 1921 u). The set.= can be pushed out by the approximate niuscles with considerable force, even in alcohol specimens.

13. iVotes on the Honaologies. Smith (18'32) considered the whole rnandiblo t o be represented

by tlie lorum, while both set= were derived from the nia,xilla, as also were the maxillary plate am1 the labium! He seeins to have strained his in te rpe ta t ion to accord with cc priori conceptions drawn from a study of the Dipterous condition. I n more detail lie homologized the niaxilla.ry plate with the palpus, the rostrum with tlie subgalea.+ga.le:i, and tlie two set= with the lacinia and stipes respectively.

hlarlatt (1895) considered our frons the clypeus and our ln1,rniri-epipliary~ix the labrum or rather pzrt of it. The lorum was considered a " m:Lndibula.r sclerite " bearing the same relation to the nirr.ndib111a.r seta as the maxillary plate or sclerite to the corresponding sekt-a view still much held in some qimrters, e. y. Comstock.

Meek (1 903) did a very detailed piece of work, and was one of tlie few cicncla. workers to notice the salivary canal. He considered tile frons to be correctly Eioniologized. hlarlatt was followed r e p d i n g the " mandihular sclerite " or lorurn.

,Just before Meek, Bentley (1 900) considered the frons, in our sense, tlie clypens.

Berlese (1909) studied both the nyrnphal and a.dult heads, but adopted :t terminology which h a s few adherents. Our v e r t e x is cn.llecl tlie post_f'ront, while o w t,riangnI;Lr appendage of the frons bea.ring t i i t : median ocellns is the tergite of the antenna1 or second Iiea.d-somite, of which the sternite is coustituted by the a.ntenna1 shelf (p. 86, fig. 41). Unfortunately, the different sections of Berlese's trementlous work are not always consistent i 'nter se, so that, for iiistance, our frons, usually called by Berlese prefronte (p. 86, fig. 41) on fig. 422, is Inbelled clypeus. The adult head is considered more especially on pp. 98-99, figs. 58--60, where the clypeus is so labelled, except a. small a.nd riot really differentiaterl portion which is called Zubmnb, our labrum- epiplmrynx not appearing in any of his figures, having been prolxlbly boiled off in caustic potash. The labium is said t o consist of submenturn , nzentu?n, and a.ppeiida.ges (lobi). The hypopharynx is considered (p. 365) to form the floor of the labial gut,terl aiid to be produced backward into the head as a peculiar process, wliicli is evidently our text-fig. 6, v.

They recognized mid pointed out t he importance of our frontal suture,

Muir ant1 Kersliaw (1911 a ) considered ndult structure.

MORPHOLOGY OF THE CICADIDAZ. 377

called " mandibular sutiire," ant1 describer1 tlie niandible articu- Intirig by a " t rue giiiglynius articii1:ttion " a t t h e posterior elid of th i s suture. The articulation point is taken as a landiiiark between f rom and clj,peus, m t l oitr present frons is therefore tlesignated cZ!jpezis. A vei'y good :tiit1 clenr account of the rnechnnisni is Gppeiitlecl.

Tlie vitriie writers (1911 b ) made embryological studies on a Reduviitl Heteropterou, demonstrating, as Heymons (1899) liacl alrea.dy somewhat indefinitely inclicated, t h a t t h e iiiandibiilxr setx ant1 i ts :xtual base develop from t h e entire iiianrlible. A t t h e sanie time they confirnied Heymona's demonstration of t h e early tliff'erentiation of t h e ni:txill:t into iriaxillnry plate a r i d seta.

A thi rd paper by these aur,hors (1 91 2 ) considered the nyrnplial head of tJhe cicada aricl t h e embryology of tlie Sip'hanta (Fliiticla?) head. The results corifirniecl those previously announced.

Snodgrass (1921 a ) gave a very clear arid bea.utifully illiistrated a.ccourit of tlie head of Septe?zdecim, with r2 critical disciission of previous work, iiiaking also it suggestive coniparison with a n Acritliaii l i e d . He considered t h e froris t o be lioiriologized as we liave stxted, and called our la.~)riiiii-ephipharynx t h e labruiii.

The saine writer (1927), iiifluencecl I)y his new decision tliat tlic second enlftrgeineiit of t h e footl-caii:tl is t h e true pIi:ii*ynx, believes t l i i i t t h e f r o m should be knowii ns the post-clypezis, :rritl tlie clypens, i n o w sense: t>he ante-ch~pe~~cs-a view in which we cannot follow him, but which is discussed in tlie account of t h e footl-canal .

Mnir (in Zitt., a.iitl in 1926) now believes tliat our frons slioultl I,e so-c:illetl, or perlraps cb~peo-ii.or,s. !L'lie cliitirious piwe supporting tlie posterior l i d f of t h e ph:tryiix or snckiug-primp is corirpnretl with t h e frontal plate of some Orthoptcra., ixiicl i s slioxii t o be tentorial rahlier t1ia.n stoiiiot1:wl iii origin.

Tlie chief debated points in the literatiire tliiis reviewed concern tlie homology of t h e large, strintetl? facial sclerite, and with i t t h a t of all tlie other pieces of tlie face, anti, secoiidl~-, tlie intet~pretntion of tlie tentorial structtires. If t h e chitinous trough wliicli supports iiiost of tlie srickiiig- pump is, as illuir suggests, tlie frontxl place of t h e tentorinni-to wliicli i t was com- p:i.recl also by Snodgr,ass (1921, p. 2),-theii t h e striit coiiiiecting i t witli t h e rest of tlie frontal apodeiiie niarks t h e inoagii:a- t ion of t h e anterior a r m of t h e tentorium. Ant1 as this iiiv;igiriation is generally accepted as inn.i,l;irig t h e boundary between frons n.ricl clypeus, t h e striated facia! sclerite would be t,lre frons. This was t h e T-iew of Sriodprass (1921 cc) arirl of Meek. I n Heteroptern, Bugnion and Popoff (1911, 11. 650) woultl seem d s o to agree mlien they s ta te "plus en arrihre, les bords de 1'6pistorne (clypeus) formrnt tleux petits ailerons (figs. 2, 3, a;.), qui doiineiit a t tache pm Ieurs amgles posttdiieurs aux branches nnt6rienrs du terltorium. . . ." Btit they believe t h e facial sclerite in question to be t h e clypeus ( i p i s t o ~ z e or c h q x ~ o n )

I 1 l l i e s:div:iry climnel of t,lie mxxillnry set:e was riiissed entirely.

378

I)ecaiisi? i t gives insertion t o t h e pharyngeal dilator iniiscles- ‘( line tles ca.r:ict&istiques cln clypeus est qu’il donne insertion par sa face profontle a a x fasceaux aritk-ieiirs du clilateur du pha.rynx.”

Snor1~r;xss (1921, p. 1) ca.lls the siinie piece tile frons for tly the same reason t h a t t h e French writers named it clypeus. e prominent ridged facial plate (36.) is designated t h e fj.ont

IieciLiise of tile att:tchinent of the pli:tryngeal muscles t o it as i n other insects.” The clypeiis of the two Frencli workers would tiiei.efo1.e a,ppexr to be t h e front of general morphologists. Siio;igrass, however, believing now t h t the t r u e pharynx is t h e secontl en1;tigerrient i n t h e alinienta.ry canal of cicada (see section 011 digestive system) and t h a t his “ pharynx ” of 1921 is a Iiioilifiietl niontli-ca.rity, has changed his rien-s on the homology of the striiitecl sclerite accordingly, and identifies t h e t r u e front with t h e small t r imgnlar piece bearing t h e median ocelliis and coiisitleretl by 11s a part of onr frons, which Sriotlgrass iiow coiisitlers largely clypeal, a s did Mnir a n d Kershaw (1911, 1912). I Int, i n the rrie;l.iitiiiie illuir has decided t h a t iie was ln i~ ts l ien i n liis former v i e w on t h e tentoriuiii, and now s t ~ v a l ~ c e s the views

fortli :it the lieginning of th i s paragraph, accoding t o which t.:e disprrt,ed striated sclei,ite is the frons. Thus, ciuiousiy euongh,-&Luir and Siiotlgrass have in a sense changed places in tlieir interpreht ion.

We lii~ve seen t h a t Siiodgrass now regirds the great siiclring- piiiiip as a inotlifieil p w t of tlie inoritit-cavity ra ther t l i i i , i i a t rue l t i m r p x , since is 1i:is no general niiiscul:tr covering, b u t only t h e tlorsnl (iihtors. U n t grnnting, as w e must>, t h a t tliis suclring- piiirip is niidogons in fiuictiori t o that of non-Heinipteroiis itistlcts, tlie loss of tixitsverse muscles and t h e great developinexit

’s :we per1i:ti)s riot sufficient reasons for declining, , t o repr t l i t as also lroinologous i n structiire,

~ t , 1e:ist i t sliocvs 110 greatel. 1nodific;itioii thzn tlre t rophi theinselves, if , :LS ,211 agree, these also ive1.e tleiivecl from the hoinologous p:lvt,s of a inandibuhte insect. Moreover, we limy ask wlrnt coiistitutes a plinryiis other t h n tlie anterior portion of tIie htjoiriotl;enin. ‘l’lie tleiiiarcatiori between nioutli - cavity a r i d piiarynx, anti between t h i s and mophagus, i s surely more or less ;zrl)i trnry.

[f I\Iuii.’s present view a.s t o tlie tentorium be correct---:i.nd it \%,oultl be tlifficiilt t o explain t h e coriditiori fount1 i n test-fig. 4 0 1 1 a,np other bnsis,-tlien the :interior arms of t h e tentorium i r i t,lre previous sense of Miiir atltl liersha\v (1911, 1912) a.iic1 in tll:\t of Doering (1922) really cori~espond t o t h e dorsal a m i s ill the cochoscl i :inti other insects. The likelihood of confiising t,llese two pairs of arms was pointed out by Dr. Crampton in conversation.

nfiiir mnkes tire interesting suggestion t1la.t tlie elements of tile t,e,lboriun represent segriienhtl apodemes, a.iising at t h e edge of tire segrneiits composing tlie head. In cicada there a r e four pairs of sllcli inv;igiiiatio~is-frontal, genal, maxillary, and labial.

MORPHOLOGY OF THE CICADIDh?. 379

La6runz-e~~oi23hai?l1zx.--Tht: projecting portion, or the ~ l i o l e , of th i s terniina.1 sclerite of t h e face 1ia.s been c:illed t h e Z G C ~ Z L ~ L by niost of tliose wlio identify tlie Iar,ge, stri:xtetl, swollen pl:i,t,e :is tlje froiis (Snodgrass, 1921 ; Meek, and Tower in Heteroptei,:r), a n d epiplia.ryrix by those who name tlie directive sclerite t h e clypeus. &feel< won1 d distiii guisli :I. r nt l i inentary 1 :I 1 )iw ni , d eep1 y groovetl iLnd oaerlyiiig tlie epipharynx. Muir ant1 Kerahaw (1911 a, p. 2) s n g g e s t tha t the division between 1:abriim (our clypeus) ant1 epiph:i,rynx is r i o t tlistinct, and therefore t h e piece niiglit he cwlled z~hruin-epioi23har?/ii~ as in Diptera. But witli t h e lioinology suggested i n t h e present contribution t,he conipountl te1.m might , f o r t,he following reasoxis, lie retainer1 for tlie narrow termina.I piece only. If i t arose from t h e edge of the sclerite mliiclr we c.dl clypeus, it; woiild be n. simple 1a.bririn : but i ts origiii on tlie iniier surface (text-fig. 2, 1.) of t h e clypeus mid its geiiwal na.t,rire :l,s a grooretl pd, sitve tlist:tlly, are epipli:iryrige:-1.1 cli:i~.acters. Y e t tlie epiplmi’yiix, iri Insecta generally, :r.rises from t h e iriiier snrf:l.ce of t h e lnliriiin, no t of t h e clypew (Conistoclc, Inims), tllongll Packard (1898, p. 43) states : “ The epipli~.ryrix is t h e lintley snrf:i.ce or phaxyngexl lining of t h e clypeus a.nd labrum, foriiiiiig thz inenibranons roof of t h e month.” I11 these circnm- staljces we think it ntlvisnble t o re ta in the compound ntline for tJhe t,eiminal sclerite of t h e cicada. face.

WitLi regaid to t h e einbryo1ogic:il development of tlie trophi, a moril here rniist be said of Heymons’s (1899) cont,iibnt-ion, tlealt \vit,li frilly i n R h t e r section. Cornstoclr (192,5, p. 398) quotetl Heyriions i n support of t h e view t h a t t h e “ inar idi~~i i lni~ sclei.itrs ” (011r 1ol.a.) a.vc forrrietl from t h e basal par t of the rriihlyonic In;lnrlible. while Siio(lgi,ass (1921, p. 8) hrings liini i n 3,s provirjg tile corjt,r:i,ry. It behoves ns, therefore, t o see what Heynioiis re;lJly st,nterl on this qiiest,ion. He (lid definitely pi-ove tliat t,he Inaxilla, split early into a p1:i.te and &a, or ratlier into two lobes giving rise respectirely t o these strnct’iires : b u t coiiceimiiig tlie ~nn.rit]ibles lie was less t1efinit.e. The following pnsage (Heyrnoris, 1899, p. 422) is doubtless Coinstock’s witness :-

‘ 6 DR. (lie Lor;*. bei ilen I-Iomopterou sell~stiindige, tleirtjlicli von {lev Sti1-n itbgegrenzte Sceletstiicke aintl iind da. sic iin derselben RezieIjung z u tlen Ka.iitlibe!n stelin wie die L:3nrinz max. zu (]err ~7ortleren k x i l l e i i , so kiitliien (lie ‘ Lom ’ entsprechenti :L]s Lainiiiz mandibulitres hezeichrieti werden.”

DtIt Heynions evidently wished t o reg,%id t h e “ m:indibiilar Scleyite ’’ a s honiologous witli t h e niaxillary plate, though Iiis own elilhryologicaL woi,k and figures indicate no such correspondence.

( 6 Diese S O ~ . Lor& sind in entjwicklnngsgeschielitliclier Hillsiclit keine ganze einheitlichen Bildungen, incleiri sie sO~ol11 ituf Restandtheile des Antennensegmentes wie aL1f

solelie des Mmdibelsegments zuruckzufnhren sind.”

T i i u s (1 899, p. 422) :--

380 UR. J. G. MYERS O N THE

And flirther (p. 440) :- " Vom anatomisclien Standpunkte lassen sie sicli rleswegen

iiiit den Lmi i i ia mnxillares vergleichen, weil sie wie tliese d ie TnsertionsflSclie fkr die Protractormuskeln (Mandibnlare Pro- tractoren) en thdten . Entmickliingsgeschichtlicli hnbe icli dugegen nicht deli Nachweis f iihren lriinnen, dass an cleni A ufbnii tler Lamin= niandibulares sicli anch noch die Extremi- tiiten tles Manclibularsegnients betlieiligen " (11. 438). " Die M;i.nc[ibel wiinle derngemiiss :~Iso irri wesentlichen n u r noch clie Inorpliologische Redeutung einer ' Lade ' besitzen."

In view, therefore, of Muir itnd Kersliaw's work, it niay. be tnken :IS established t h a t the whole of t h e embryonic mandible develops into the seta and i t s base.

'1'0 siini up th is section, we ma.y regard three other points in cic:b(la. head morphology as settled :-

(2 ) That t h e sclerite on each side, which we have called tlie l o i ~ i m , is :I par t of t h e genn, ancl is neither a. lateral development of t h e clypen.1 region, as Muir ancl Kerslinw (1911 6, p. 78) heliet7etl, nor t h e sole remains of the functionless nia,nclible (biiiith, 1892), nor yet :L iiiandibular sclerite (Meek, Marlntt, and ot,hers). 1 1 1 th is interpretatioii Muir, according t o iiix latest paper ( l926) , agrees witli Hnodgrnss.

( 3 ) Thak t h e i i ia ,xi l l~ w e represented on each side by n bnsa.1 pI;Lte miiich becomes inore or less fused with tlie hend-cnpsitle, ancl :I, t1ist:tl setn which witli its fellow forms t h e second or inner p:rir of r o s t d setre. This follows from t h e embryological morlr of 1Ioyinoris :rnd of Muir and Kershaw, a n d as Sriocigrms (1921 a , p. 8) tins said, iniist be accepted until new embryological evidence is ;rtl~lacecl t o t h e contrary.

($1 6' AII writers, except Smith," writes Xnorlgrass, " agree tl1;t.t the labinrii of t h e adult is formed from tlie fused labial :Ippendn.ges of t h e embryo.'' Muir would c d l t h e basal segment i n cic:i,da t h e ?miztzLnz, tlie second, which is somewhat swollen, the pcdpigei. ; aiid tJlie third the ZigrbZa. Rerlese (1909) terms the P:I nie segnieiits srdiiaent~cn~, ?izentrtnz, and lobi, while Marlntt (1895) calls tiiein submentuna, mentuni, 2iqttlcc.

rl. TIIORAX AKD ITS APPENDAGES. CX. '7%03'(135.

s i n so many other ChiLracters, there is coiisiderahle homogeneity in thoracic s t ructure throughout tlie family. A ii,jticenl,le featnre is t h e greatly eiilargerl mesot11ore.x and esl)ecia.lly i t s notuiii, doubtless associated with t h e very s tout and powerf ill fore-wings 01- tegminn. I n t h e nymph, 011 t h e other Iinncl, tlie prothorax, carrying the niuscnlature of t h e strong fossorid fore-legs, is much t h e largest of t h e thoracic segments ; n,rld srlch is the condition in t h e imago of Te'ettigoi-ctcc, where t h e hyprtropliiecl pronoturn (text-fig. 8) overshadows t h e much

MORPIIOLOGY O F T H K CICAD1O.E.

Text-figure 7.

38 I

Meelampsalta nzuta (Fabr.). Thoracic nota.

p . , pronotum ; ms., mesonoturn ; mt., nietanotuin; ce., cruciform elevation (scutellum).

Text-figure 8.

Zbttigcrrcta crinita Dist. IIpad and nota shoiving the tremendously enlarged pronoturn.

reduced mesonotum. In this primitive form the tegminn are far vveaker, without that inassing of veins on the fore-border 50 characteristic of all other cicadas. I n these latter, however, the

PROC. ZOOL. Soc.-I 928, NO. XXVI. 26


pronotum is the second largest of the thoracic segments (text-

The only worker LO deal especia.lly witli thoracic structure in Cicntlitlze is Taylor (L. H., 1918) who used il'ihicen linnei 8. & C:. (Cicada tihicen n w L.) arid Cryptotynapana epithesia Ilist.

fig. 7 , p . ) .

l<erlese (1909) gives considera,ble details. Our description and figures are based largely on iWeZanapsalta

Three pairs of small, free, cervical sclerites are present. In the prothorax the notum is curved down considerably

laterally. The surface is mmked with deep grooves associated with muscle insertions, though !raylor would regard them as division marks for a triangular prescatum, a scutum narrow mesally and wider a s it approaches the pleuron, and a scwtellum. -We believe this to be entirely fanciful, as, indeed, Crampton * has indicated in Dissosteira (p. 350) when he says tha t the sulci of the pronotum divide the surface into areas which have been very incorrectly identified as prescutunz, scutum, etc., although they are purely secondary structures having no connection with the typica.1 notal subdivisions of the wing- bearing segments.

The pleuron of the prothorax is grea.tly reduced and practically fused with the notuni. The fusion concerns chiefly the epimeron, while the episternum is more reduced.

The prosternurn is represented by a single plate bearing the well-developed furca of the endoskeleton. The plate may be regarded as a fused eusternum and sternellum.

The mesothorax, as me have seen, is the largest division of the thorax. The anterior. part of its notum projects beneath the pronotum almost to the occiput, and this part has been distinguished by Taylor as the anterior phragma (prophragnzn of Herlese). The presc.utum is only indefinitely rnarked off by sutures beginning along the outer edges of the dark obconical marks which form an almost constant feature of cicada markings (text-fig. 7). These correspond to muscle insertions. The greater part of the notum is occupied by the scutum, but the scutellum is sharply diEerentiatec1 as the cruciform eZevatio?L of taxonomists (ce). The posterior edge of the scutellum runs down laterally to give insertion to the axillary cord of the tegnien. The scutellum entirely hides from dorsal view the strongly- chitinized post-scutellurn or post-not urn, which forms a shelf beneath it. The post-scutellum is joined to the epimeron by a ~~a i - row bridge (text-fig. 9, poa.) called by Taylor the postdare, which is just the prolongation of the katepimeron.

On the pleuron the pleural suture is distinct, and in addition there is a suture dividing the episternum into an upper anepi- sternum (aes.) and a lower katepisternum. The latter suture is coiitinuons posteriorly across the pleural suture, and there divides the epimerori in the same way, a condition said to be peculiar to

Soc. Am. xi. pp. 347-366, pl. 32. text-fig. (1918).

ci'iagulata and iM. nztcta.

* " The Thoracic Sclerites of the Grasshopper, Dissosteira carolinn," Ann. Ent.

YORPIIOLOGY O F TIIE CICADIDB. 383

the Cicadidae. A t the lower extremity of the pleural suture the coxal region shows a distinct posterior meron (me.) and t rue coxa (c.). I n Cryptotympanffi Taylor found that a median portion was marked off on the episternum between what we have called anepisternzcnz and 7catepister.nzcn~ respectively, and this tripartite condition recurs in MeZffimnpsalta (ms.). It will be interesting to study its occurrence throughout the family.

I n the mesosternum of Xelampsaltffi a eusternum or basisternite (e . ) and a sternellurn or furcasternite are to be distinguished. The invagination in the latter to form the furca presents externally a deep and wide mouth. The trochantiii (text-fig. 9, tn.) is normal.

Text-figure 9.

aes.,

2Kelampsalta sericea (Wk.). Nesopleuron. anepisternnm ; aem., anepimeron ; ms., median division of episternuin ; e., eusternnm ; tn., trochantin j c., true coxa ; ks., katepisternum ; k e i ~ . , katepimeron; me., meron ; p a . , postalare; sp. 2, second spiracle.

The inetathorax is extremely short, especially dorsally, where the whole notum is reduced t o a narrow band (mt.) behind the scntellum of the mesonotum. The posterior edge runs down laterally to the axillary cord of the hind wing.

I n Taylor’s two species and in Melffinzpsaltffi the pleuron shows a distinct pleural suture dividing off an anterior episternum (es.) and a posterior epimeron (em.) , both of which remain undivided further (text-fig. 10).

“ The epimeron of the female is large and rectangular. I n the male n broad lobe, called sometimes the operculum, extends backward from the epimeron and sternum. . . . .”

We believe that the operculum is purely epimeral. I n Xepteizdecim it may be seen distinctly to curve round the posterior

Taylor (p. 2 3 2 ) writes :-

26*

384 * DR. J. G . MYERS ON THE

margin of the sternum, towards its fellow. Moreover, the sternum has a distinct process of its own to which the folded membrane is attached. W e shall discuss these structures in more detail in connection with the rest of the sound-producing apparatus.

The metasternurn shows a eusternum (text-fig. 10, s.) and a sternellum (st .) . The trochantin occupies its usual anterior pc!sition (tn.), and must not be confused, as is so often done, with tlie meracanthus (mc.) of Fiebei-, which is a spur arising from the meron.

l ' h o m c i c Endoslceleton.--The furca of the prethorax is very strongly developed, the others less so. The chief peculiarity of the endoskeleton is the great development of the mesophragma, giving insertion to the great lateral muscles of the mesothornx (costccli-dorsccli of Berlese). This pliragma is called by Berlese the preclaaicoln clel metanoto. But i t seems to 11s to arise

Text-figure 10.

mc

itfelampsalta muta. Female : metasternum etc.

s., basisternite (eustcrnum) ; ps., pleural suture ; mc., nieracanthus ; es.,epistcrnum ; em., epimeron ; op., operculum; st., sternellum ; c., coxa; tn., trochantiu.

distinctly from tlie postnotum of the mesothorax, and thus to be a postphragma of that segment. Taylor (p. 230), with views evidently colourerl by Berlese, writes of the post-scutellum or post-notum as *' fused with the anterior phragma of the metathorax," but gives no evidence that the pliragma in question belongs to the metathorax rather than to the mesothorax. We may, of C O U ~ ~ C , beg the question by admitting that in the last analysis, since a phragma is a plate invaginating betwrem segments, i t belongs to neither. Hut Crampton, in his work above cited on Dissosteira, makes the definite statement (11. 354) tha t the post-scutellum of tlie metathorax bears a pliragnia for the attachment of tlie longitudinal muscles arching the notum in the movements of flight ; arid similarly, in an earlier paper *, " The posterior plate , . . . or post-scutellum usually consists of an external region bearing an internal phrsgma."

Imms, moreover (1925, p. 47), would appear to hold the same * G. C. Ciampton, Zoologisch. Anzeigrr, xhr. p. 60 (1914).

MORPHOLOGY OF THE CICAUIVE. 385

opinion. W e therefore name as mesophragma the great plate which cuts off the whole of the fore-part of the body from the rnetathorax and abdomen, leaving a narrow perpendicular slit for the passage of the viscera and nerves.

ZL'eZatioiLsh~pps.-Tlie tripartite mesothoracic episternum is considered by Taylor a nenropteroicl character. Cramptort has :dso usell thoracic structure as an argument for neuropteroid relatioilships. According to Taylor the threefold division of the

Test-figure 11.

Melampsalta muta. Female abdomen : ventral view; ovipositor largely disengaged.

I.-IX., abdominal segments ; 6-9, spiracles ; m., mirror (tympanum of chordotonal organ) ; a., auditory capsule.

episternuni is present also in Cicadellide (Jassoidea). The composite mesothoracic epimeron would appear to occur in no other Homoptera.

p. Legs. Hansen has made a detailed study of the legs (1890, trans.

The prothoracic legs of the Cicadas are highly characteristic both in the nymphal and imaginal stadia. The femora of the first (see later section) are much swollen and strangely modified for fossorinl purposes; those of the second (text-fig. 15) are

1900-1903).

386 . D A . J. G . MYERS ON THE

enlarged almost as much, and furnished ventrally usually with three %tout spines, directed somewhat obliquely. The trochantins, as we have seen, are distinct, the coxre very long, with a considerable distal portion free. The interior angles of articulation are a t a considerable distance from the insect’s middle plane (Hansen). The trochanters are thick with a very oblique femoral articulation, producing a see-saw movement.

Text-figure 12.

Xelamnpsalta wtutu. Male : front view of right fourth spiracle.

m., mirror; a., auditory capsule.

The second and third pairs of legs are unspecialized, showing a probably primitive simplicity. I n the second pair coxre are moderately short and broad, and situated near the middle plane. Their principal movement is rotary (Hansen). There is no t rue meracanthus, but t,he meron is well developed.

I n the third pair the cox%, according to Hansen, are the

Text-figure 13.

~ r ~ 7 ~ m p s a Z t a muta. Male : lateral view of parts of segments vII.-IX. to show position of tenth (and last) spiracle.

sinlplest in the Auchenorrhyncha. They are contiguous in the middle plane and articulated in a pagiopodous manner, i. e . only a hinge-movement is possible. The meracanthus is usually well developed.

The tarsi are usually three-segmented as in all other Auchenor- rliyncha, bu t Cicadidae differ in lacking any empodial formation.

MORPHOLOGY OF THE CICADIDAC. 387

The claws are two-equal, stout, and simple. Those of the nymphs, as first indicated, but not described, by Hanseri (trixnsl. 1901,.p. 151), are very different from those of the adult.

I n the universal habit of cicadas to rest habitually in a perpendicular position, whether the support be trees, herbs, or

Tdxt-figure 14.

jpfelantpsaZta muta. Female. ventral view of base of abdomen. sp. 4, fourth spnacle; S.I., h s t abdominal sternite; S.II., second ditto.

rocks, we may see an explanation of the powerful fore-legs. The attitude is largely a suspensory one. in which the second and third pairs take little part, most of the weight fnlling on the prothoracic pails. A similar condition occnrs in certain moths.

Text-figure 15.

ZeZampsaZta sericea. Fore femur, inner view.

y. The Wings. Chabrier (1822), Amans (1885,1915), andImhof (1901,1905),

also Haupt (1913), have devoted considerable study to cicada wing-structurs from the viewpoint of t he mechanics of flight. Cornstock and Needham (1898), in their first classic attempt to homologize the wing-veins in all the orders, studied cicada venation in detail and ascertained its condition in the nymphal wing. Their interpretation, with the Tillyarcl modifications, has


been adopted in this paper. Woodworth (1906) dealt more 01- less incidentally with cicada venation, ancl drew attention to the nodal line, miased by Corristock and Nieedhnm (at least in text), but considered at greater length by HorpAth (1913) in a paper whish introduces several divergences from the Comstock-Needham interpretation. Berlese (1909 J pays considerable attention t o the axillary sclerites.

The first taxonomic division of the family w ~ s based, Iinsuccess- fully as events have proved, on the wing-venation, while Iatm workers have used i t for generic separation.

Comstock‘s latest account (1918) is apparently identical with that of Comstock and Neeclham’s original coiitribution, while iVloolton’s account (1923) ancl figure follow Horvath. Conistock’s

Text-figure 16.

Melampsalta sericea. Lateral view of male abdomen.

I.-X., abdominal segments j fm., folded membrane.

type was l’ibicen ; ours will be chiefly Melunipsalta muta, with which we lime attempted to compare other members of the family. Text-figs. 49, 50, and 5 3 are to the same scale, while 48 and 54 are more enlarged.

i. Tracheatiom. A transverse basal trachea exists between the costo-radial and

the cubito-anal groups of pre-venational tracheE in the developing wing-base. I n this respect cicadas a le less primitive than Membracidq Cercopidae, arid some a t least of the Cicadellidz, where the basal connection is absent-a condition tha t exists nowhere else according to Comstock (1918, p. 275), but in Plecoptera and certain Blattids. Cornstock has shown tliat when this transverse basal trachea is present the medial trachea tends t o migrate along it towards the orbit-:ma1 group. This is well shown in cicadas, and reaches an extreme in those cases where the M and Cu are united in a common stalk a considerable distance after entering the tegmen (text-figs. 48, 49 ; cf. 50, 55).

MOltPIIOLOGY OF THLE CLCADIUB. 389

The tracheation is of the simple type, in which only the principal veins are represented by pre-existent tracheae. The nymphal scheme is much more primitive than the adult venation would lead one to suspect, and, in fact, it approaches very closely to the Comstock-Needham hypothetical type- The great reduction of H 1 is a striking difference.

ii. Vencctioiz. In the following interpretation we have followed, in company

with Muir, Imms, Alexander, and many other workers, the Tillyard modification of the Comstock-Needham system, considering the latter's 1 A to be really Cu 2 .

Text-figure 17

.NelampsaZta muta. Male : lateral \iew of left sound-appaiatus. t., tymbal; sp. 3, thiid spiracle; op., opercnlum ; a., auditory C R ~ P U I P ; nz., mirror.

First is a description of the venation in Melanzpsffilfcc mtctffi, and then n discussion of divergences i n other members of the family. T h e orthodox abbreviations need no explanation.

I n the tegmen (text-fig. 48) there is a conspicuous massing of veins on the costal margin ; but the elements are distinguishable under magnification. Costa is very thick and coincides with the margin of the wing. Sc is fused with R, at lenst as fa r as the noclrtl furrow, which will engage much of our attention later. R I is apparently obsolete in the imago. The fate of the other branches will be apparent from text-fig. 48 (cf. 49, 50). The

390 DR. J. G . MYERS OK TUE

base of M is in close contact, if not actually united, with the common Sc + R stem until the arculus is reached. There M splits off to form the anterior arculus and to join Cu, by which latter fusion the posterior arculus, seen in more typical cicadas (e. g. il’ibieen, text-fig. 5 5 ) and representing the cross-vein between M and Cu, is obliterated. So far we are in accord with Comstock and Needham, save for the differences in the species described. These writers state that there is a peculiar and unparalleled condition in certain insects, including cicadas, consisting in the fusion of 1 A with the base of Cu, so tha t it appears a branch of Cu, far separated from the common stem of 2 A and 3A. Tillyard has given good reasons for. considering their 1 A as Cu 2 , thus making Cu two-branched-a far more probable explanation

Text-figure 18.

Melniirpsalta serieea. Male : lateral view of right sound-apparatus, with segments softened and stretched to fullest extent.

op., cut base of operculum; c., metacoxa; fm., space normally covered by folded Other letters as in text-fig. 17. membrane ; ms., metasternum; mt., metanotnm.

of the condition. The anal furrow lies along the conjoined courses of Cu 2 and 1 A.

The venation of the hind-wing is niore specialized than tha t of the teglnen, the difference depending, in Comstock’s opinion, on the more nearly basal forking of R in the former. From this it results that only R 2 + 3 fuse for a considerable distance with S c ( R 1 being completely lost), while R 44-5 coalesces for a short distance with M. The common Sc+RZ+Y stern is in close contact with C, and in i‘httigai-cta (text-fig. 53) seems actually fused with it. While M is normally only three-branched, there occur aberrations in which exists a small remnant of cell M 2 , usually crowded out by coalescence of M 2 and M 3 ap in our fignres. ‘This venationnl variation is only one of many which

NORPHOLOGY O F TEE CICADIDB. 39 1.

occur witb frequency in all genera of which I have seen sufficient material for comparison, and such characters should be introduced with great circumspection into taxonomy, even when they appear constant. Pauropsalta, founded by Godirig and Froggatt on such a venational difference, I do not think can stand, and Bergroth (1911) has been critical of some of Distant’s siniilar characteri- zations.

Applying the Tillyard correction in the hind wing, we find in the adult (text-fig. 54) that Cu branches in a U-shape right at the base of the wing, and the two branches become considera,bly septrated, Cu 1 dividing into Cu 1 a and Cu 1 b, while Cu 2 runs in the anal furrow with, but really separate from, 1 A. The

Text-figure 19.

b-

--

m

Mngicitadu septendecim (L.). Male : KOH preparation of mirror and adjacent parts, flattened out.

fin., folded membrane; i., inteisegmental membiane between thorax and abdomen ; I., II., abdominal aternites ; m., mirror; p . , process to chordotonal organ ; t., tymbal; w., wing (see p. 466); a., auditory capsule.

two remaining veins, by this interpretation, are 2 A and 3A respectively, thus being avoided the Rnomalous attribute of four anal veins, or a two-branched 3 A , required O K ~ the Comstock hypothesis. The anal area is much more developed in the hind wing than in the fore, and folds under the corium when at rest.:-

Finally, both tegmen and hind wing are surrounded by a strong border between the ambient vein (text-fig. 48, an&) and the edge of the wing.

Venation in the Fumily.--l\lain features, as described above in Melampsalta, recur throughout the family, save in the subfamilies TettigarctinE and TettigadinE.

Net-veining of the tegmen, a character on which Amyot and Serville based the first classification of the family, has almost


certainly arisen independently in several different branches of the family,and occurs to-day in several unrelated genera :-Polyneum, Anycc~nirma, Talai?zgcc, Eenridictya, and others. The condition, moreover, in such a form as Polyneurw, brought about by ercessi\ e regular dichotomy of the longitudinal veins, differs grettly from the network of irregular cells found in the Hemi- dictyirie forms.

Lenz3eju (text-fig. 56) and Cystosonzcc show a more or less complete abkentse of the coriaceous border on the tegmen, the ambient vein coinciding with the margin, which it slightly thickens.

Text-figures 20 8: 21.

21.

Magicicada septendecim. Female : as text-fig. 19. Internal view. ac., ieitiges of Vogel's rudimentary abdominal coxites I. and 11.; I.-111.

abdominal sternites; p., left member of pair of pores of unknown function ; .$., flap (see text).

Pig. 21. Portion of the same preparation as in text-fig. 20, but with flap turned forward.

More fundamental differences occur, as we have mentioned, in Tettigarcta and in the Tettigadinz, which show between them a gradation leading up to the specialised condition of the dominant and more typical cicadas. Venationally there is much more in conimon between Tibicen and Xeelanzpsabta, which are separated as far as possible under the present classification, than there is between either and Tettigarcta. Yet the present scheme places the latter with Melumpsalta in the same subfamily.

Y'ettigarcta is a t the very base of the Cicadide, and is extremely

MORPHOLOGY OF THE C1CAI)ID.B. 393

primitive in far more respects than absence of sound-organs, and not least so in venation.

The TettigadinEe, of which we have examined Chonosia cmss i - pemais (text-fig. 49) as a type, connects it, venationally only, with the dominant groups, and so may be described first.

In the first place, Chonosia shows a distinct strongly-marked membrane fold along the nodal line, to be discussed later.

Secondly, Cu 2 lies, as usual, in the a n d furrow or on the cltwal sutnre, but considerably distant from 1 A, both basally and distally, as pointed out in the characterisation of the subfamily by- Jacobi (1907 c). The strondv-chitinized base of the clavus a t . " the point corresponding with the posterior

Text-figure 22.

tuberosity of Amans

NIeZnmpaZta Zeptomera. Ultimate female nymph : junction of thorax and abdomen extended to fullest extent. Lateral view, right side.

mt., metanotum; sp. 2, second spiracle: ac., region of future auditory capsule; a., region which in male develops future tymbal; c., metacoua.

i s said to be strongly developed in the whole subfamily Tettiga- din=, and is supposed to form a plectrum for the stridulating apparatus on the mesonotum (text-fig. 59). In Chonosia crussi- p e n i ~ i s I do not find that it is much more protuberant than in other Cicadids, and Mr. W. E. China, from experiments with a softened specimen of a Tettigccdes, expresses grave doubts n s t o whether this structure could be employed as a plectrum. Un- fortunately observations in the field are lacking.

I n Te'ettiyarcta (text-fig. 50) the whole tegmen is markedly coriaceous, the basal half especially so. The surface is covered with irregular shiny taberculations. The nodal line is extremely distinct, as well on the membrane as on the veins themselves.

The anal furrow is very deep, the vein Cu 2 on its floor rather weak. The ambient vein is normal, but the coriaceous border

394 DR. J. G. XYERS ON TEE

somewhat narrow. The main veins bear long hairs. Costa lies widely separate on the fore border of the tegmen, with a large costal cell between i t and the Sc, R, and M group. There is thus practically none of that nrassing of the main veins on the costal bortlev SO noticeable in other cicadas. The strong longitudinal grooving of the tegmen may counterbalance the general weak- neb? due to this lack. This folding is very conspicuous, the costal cell and the anal furrow being especially depressed. Cu is peculiar (text-fig. 50j; it forks early, and Cu 1 goes up to join M at the inner end of the anterior arculus, where the prominent boss on the surface of the tegmen makes the course of the veins difficult t o follow. 1 A is extremely distant from C u 2 and is strongly convex, lying on the brink of the deep anal furrow.

Text-figure 23.

Jielampsalta cingulata. Male : KOH preparation to show junction of abdominal tergites arid sternites.

]IT.-V., abdominal segments ; t., tergites ; s., sternites; 5-1, spiracles.

The cross-ridging of the tegmen (see later) is practically obsolete, probably owing to the coriaceous texture. "lie venation on the whole is strong, standing out in bold relief.

'Che hind wing of Tettigumto (text-fig. 53) shows, as usual, more specinli~ation than the tegmen. The hind wings of the Cicadidz as n. whole are mere appendages to the stronger and larger tegniina. Sc and R 2 + 3 a le fused as far as the distal part of the wing-coupling apparatus (see later), where the common stem forks, apparently into Sc arid R 2 + 3, so that a large additional cell, Sc, i s formed. I n conjunction with this the cross-vein Y between R 2 + 3 and R 4 + 5 is carried very much nearer the apex of the wing. The cell Sc is squeezed out by vein coalescence in most other cicadas. A vestige is visible, almost hidden by the wing-fastener in the l'zbzcen chloronzei-a figured (text-fig. 51).

MORPHOLOUY OF THE CICADIDE. 395

The anal veins are distinctly three, arising from an apparently common base and spreading beautifully fanwise in a primitive fashion. Practically the whole surface of the hind wing shows innumerable microtrichia, which appear t o be absent on the tegmen. The coriaceous border is as in the tegmen.

The axillary membrane in Cicadids is well developed and frequently coloured, when it affords a good taxonomic character. It contains the axillary sclerites, and is bounded posteriorly by the axillary cord (text-figs. 50 & 59, az.).

The ccbseizce of R1.-Muir (1923, p. 217) writes : “ The

Text-figure 24.

t

si. 5

HiH Metampsalta sericea. Male : external view of left auditory capsule. t., position of tymbal; a., auditory capsule; sp. 5, fifth spiracle.

absence of a distinct free Rl in the adult tegmen is characteristic of most of the living Auchenorrhynchous Hornoptera, but it is found in the Mesozoic Cicadid, Mesogereo~ Tillyard.” We have seen that the R 1 trachea occurs in the nymphal wing of Cicadi&e, as also in that of Membracide. But I believe that the presence of R 1 in ilfesogereosz is only apparent-that it depends on an interpretation of Mesogereon tegmen different from that given here to the cicada tegmen. If we compare Tillyard’s figure (1921, fig. 66) of Mesogereon tegminal venation, not with that of a typical modern cicada, but with tha t of l ’et t igwcta (fig. SO), which shows an intermediate condition,

396 DK. J. G . MYERS ON TIIE

R in both cases is seen to end in three branches meeting the margin of the tegmen or, rather, the coriaceous border. The condition in Mesoyereon has necessarily been interpreted from adult structure only, and the first of these three branches has therefore naturally been called R 1, as indeed would probably the first of the three radial branches in Tettigurcta and also in more typical cicadas, did we not know from the nyniplial tegmen of the latter that the true R 1 is lost in development. Therefore there is no proof that the first branch of R is the adult tegmen of iWesogereon is other than homologous with the first branch of R in modern cicadas, which we know from ontogeny is R 2.

The p e s t i o n of Costa.-I have followed in the foregoing the commonly-accepted Comstock-Needham interpretation of the anteriormust vein of the tegmen as C, since this view is based on,

Text-figure 25.

As text-fig. 24, but viewed internally. m., mirror (mostly out away) ; p., process to chordotonal organ ; ac , auditory

capwle; sp. 4, trachea enterlug from fourth spiracle ; t., shows position of tymbal.

arid seems to accord best with, the evidence from nymphal tracheation in Cioadidze.

This vein, however, may not be true C. The recorded nymphal evidence in Auchenorrhyncha as a whole is conflicting, since in some forms the corresponding trachea seems to arise from the alar bridge, and in others from Sc, in which latter case i t is apparently homologous with the humeral. Muir (1923, p. 216), in discussing the whole question, notes wit,h reference to Fulgoroida :-

“By calling this vein the costa we are faced by the fact that, in a large proportion of the fulgorids, t he costa vein and costa margin do not coincide, but the vein lies considerably within the membrane, leaving a precostal cell o r costal area. This is a condition recognized in no other order of insect,^."

NOEPIIOLOGP 01 TIIE CICADIDB. 397

Similarly. Tillyarcly states :- "I t seems, however, very iinliltely tha t any t rue costal vein,

distinct from tlie anterior bortler of tlie wing, was ever present in any Panorpoid type. seeing that such CL vein is absent Jj-orn almost all known insect wings." (Italics mine.) Conistock has bhown that R 7. is conipletely aborted (1918,

p. 272). It would therefore seem thnt if our C is Sc and our R+Sc stem thu5 R alone, even then t h o vein we have called

Text-figure 26.

Fidiilicina semilatn (Wk.). Arrow represents hair thrust into fourth spiracle, and through trachea which

emerges from i t ; II., HI., abdornind segments; s., sternites; tg., tergites ; t.,position of tymbal; a., auditory capsule; sp. 4, fourtli spiracle; sp. 5, fiftli spiracle; tT., trachea (dorsal) ariying from it and sending off a thinner rentml branch.

Internal view of male right auditory capsule.

Bc, branching oE, a t tile node, t o the fore-border, would not be R 1, buh rnther :t cross-vein betwetn R and Sc. But here again we are led into difficulties, since, as we shall show below, HorvAth is wrong in considering the vein on t h o fore-border, distttl to the node, as a continuation of tlie airteriorniost vein proxinial t o the node (his and our C). It tends to be continuous witzh the sliort vein, Tvliich leaves the R (or R+8c) stem at the node, and wliieli cannot therefore be a cross-vein.

PROC. ZOOL. SOC-1928. NO. XXVII. * Proc. Linn. Soc. New South Wales, xlir. p. 649 (1919).

27

398 UR. J. G . MYEllS ON THE

HorvBtli believes Comstock and Needham incorrect in stating that C terminates a t the node, its place on the anterior margin being taken by Sc. He claims that our Sc (text-fig. 48) is really a continuation of C past the node. T’iewed dorsally in Xe1arn;o- scclta muta (text-tig. 5 2 ) , C is seen distinctly to end at the node. Continning i t s line is a piece of similar width and coloiir, ba t flat or even hollow, being the edge of the tegmen d o n g the sub- costa. Viewed ventrally, as Horvith suggests, this continuous portion anterior to Sc does look vein-like, bnt the convexity is merely the bottom of the grooved edge of the wing. Moreover, in the nymphal tegmen, the costal ti acliea is distinctly shorter than tha t of Sc, it5 termination being a t a point corresponding with the node of the adnlt tegmen.

Text-figure 27.

M&zmpsnlta sericea. Male : back view of mirroir (9% ) and tymbal-muscles (tm., p . , proceess t o chordotonsl organ ; a., auditory capsule.

The costal area or precostal cell meiitioiied by Muir in tlie quotation above is well developed in some Cicadidze. especially i n some of tlie Platyplenrinz. Thus in Ycmga pzdveiea arid I’,,/cria n ~ ~ a d n ~ i s c c w i e ~ ~ s i s (textJ-fig. 57) there is a wide ampliation of tile fore-borcler outside the co&ta. ‘Ihis p~ecost:~I cell is as wide as (Yangcc) or wider than ( P y m c ~ ) , the true cohtal call. suci l ampliation is an element in a general secondary platyptery considerably rniwked in these a n d related genera, and accorvipanied by the tlcvelopinent of pxraoota.

iii. l ’ h e Cyoss-ridging. A striking and peculiar feature of the teginen of Xesogereoiz

and of all Gicadidzc except l‘ettiyaiatrc is the presence of numeyous cross-ridges, especially visible in ce;t;Lin lights and interpreted by

MORPHOLOGY OF TIIN: CICAUIDB. 399

Tillynrcl as arcbeclictya.1. In the Palzeontinidat there are apparently no sigiis of this cross-ridging, but the condition of the material is usually not such as to show such a character.

Forbes (W. T. M., 1922) saw thiscross-ridging in an emerging cicada of cindeterininerl species. For just a few minutes it wits perfectly distinct. The arrangement was very definite ; t he n:i.rrow cells were filled with a series of simple evenly-spaced cross-veins, while iii cells B, 1st M 2: and M they formed a double series of cells alternating with each other. On the coriaceous border beyond t h e ambient vein they were evenly speed, the regular longitudinal veins each ending opposite the middle of :L marginal cell. Towards the costa there were two veins opposite each definite cell, while opposite cells M 3 and M 4 there were three, and more posteriorly even four. The margin ‘of the hind wing was similar, but the clisc of the wing was not .observed. I n the cell 2 A, instead of cross-veins, there was a

Text-figure 28.

>&&mpsuZta serieea. Left tymbal from within to show attachment of muscle. pZ., terminal plate of tymhal-iiiusde; tn., its tendon ; t., tymbal.

series of closely-spiced parallel longitudinal veins, which remained visible in the dried wing.

Forbes regarded these transient veins as ‘* fugitive blood veins,” and suggests they are relics of a net-veining such as occurs in the h’enroptera. He believes the different arrangement in the :ma1 region especially suggestive, a,s it recalls the plaited portion of the wing in the Orthoptem, where there exist numerous ynriillel longitodind veins.

This :igrecs with Tillyard’s origirtai theory in 1916, when he H:I.IV in Xesogereon, o n account of these cross-ridges, an intermediate stage between Bugemon and the PnJ~eohemiptern. ‘Yliotrgli Ez/,gereon is n o longer considered Heinipterous, and the Pa1;eolieiniptera are disposed among recent groups, it still rc,rrinins prolnble that tliis condition is n relic of the net-veining of :I, 1’iLlreo:lictyo~)teroid or Protorthopteroid-PalEodictyopteroid ancestor of the Iiemiptera.

27”

400 DR. S. G. MYERS O N ?'HE

Gonreau (1843, p. 204) remarked that the cicidas are excep- t i o n ~ ~ l in tliat the hind wings do not iridesce: Gadd (1908 b, p. 143) very rightly contradicts him, tliough admitting that the tegniina. are certainly tlie more iriclescent. The Russian a u t h o r notices further tliat tlie iridescent wing-colours of older cica.tlas are predominantly yellowish, while those of younger ones are slip- blne.

iv. The ATodul Line. ( 1 lliis is a very reniark;thle structure, present to some degree in

the tegrrreii of all Cicadicl:t, and especially ni:i.rketl in tlie very archn,ic Ykt t igamta a.ntl in the proliably primitive ~lf"ogamm,ia, in whiclr imd in others the basal portion of the tegirien is t h n s

iterl :is :L more coriaceoins aiitl opaque part, at 1ea.st super- fici:illy vesernbling R typically Heteropterous, 6.g. Pentntonioid, coiiditjion. It is least developed in such as form 11s Melccnzpsnltu (text-fig. 581, hut a point overlooked is tha,t tlie breaks in the wing-veins where the nodal line crosses them are xlwa.ys complete,

Text-figure 20.

,?l~gicicndn septsizdecim. Male : inner view of portions of stcmites I. and 11. showing the miirgs (w.), wliicli have beeu described as an abdominal h c a .

even in those which are most divergent from the 2kttigcwc8a-liiie coiitlition, hrihof has described tlie nsn:~l coiitlition of tlie 1~ot1;d Iiiie ill 22 gcnera in very great tletnil (1'303), recogrrizing 13 e1eiiients7 mid has enumerated tile various kiritls of joints a n t 1 foitis formwl ill veins :mtl ineinhrarie by its p : i

sotnt; of tliesc joints e n l a i p i in tpxt-figs. 51 : I T

line hegins on the costxl margin : L t the tljstinct iiotle, where the fore-lmrder, e.g. in i2/leZampsalta ci~yzclnta, is ofteri howed N J I ~ ,

riiiiriing hetween the twinination of C a.nd the b:as:r.i p u t of Sc, crrt,a the S c + R stem. I t then curves in somew1i:Lt tomartis the .wiiig-h:tse ant1 bre~nks A t 2 +- 3 ant1 112 3 + 4 in siiccesjiori, riinniug tlieu tiown Cn 1 h to the hind-margin (text-fig. 51). Zri tile doininmit modern cicnclu.s, repimerited on the one linntl by 2'ih ao(1 0x1 the other by ~l~felampsultcc, tlie iiotial line on the riieiii-

bra,ne I ie tmee i i the veins is very indistinct, bnt is aln tiys visible if t,he insect IDA held a t it certniri angle. In those fornis where t h e J i i X ~ a ~ line, as iii Xogamairc, divirles a Insal cnriaeeous, often I~rigIi tly-coloi~re;l, coriuiii from a distal transparent ~~iernbrnne ,

UOILPIIOLOGY O F ‘i’LlE CICADIDrE. 401

it IS, of course, very distinct. I n Choizosia, where sucli . I

tleinarc&iou is not present (text-fig. 49), the iiodal l ine is nevertheless very well market1 on tlir membrane. Finally, i n l’ettigccrcta the riorldl line is extremely conspicuous, rrossing not only tlir vein<, bnt forming on tlie intervening meinl,mne :I tleep groove or fold. tlie lip5 of which appear a s two fine pml ie l lines.

Iinliof (1. c.) a n d Conistock (1918, fig.) both notice t h t , the break in tlie veins where tlie nodal line crob~es is not pal ticipated in h j the t r a c h e a

The nodal line is apparently not piesenr in iWmogereo?z, and its absence, coupled with t h a t of apical celli, inakes me reluctant t o place Xesogereoib i n t h e Cicadidz a s Muir woirld do.

In the Palzontinidz, however, both it and t h e node ale present

Text-figure 30.

X e Z n n p n l t a Zeptonzsra. Feiiiale : iriiier view of left half of pygophor, the anal segmerit boiled off.

VII1.-IX., abdoiiiiiial segments; s., steriiite; t., tergite; r., cut edge of right median process ; Z., left anterior process ; my., middle piece, fused distally.

t o some degree, as evidenced by t h e published figures (Haase, H;~ricllirscli, Oppedieirn), writ1 by t h e examples studied by nie in the Musenin of Coinparative Zoologj. One of the la t ter specimens slio\vs a distinct k)reaIi i n tlie curbature of the costal border of tegnien, with au inwvartlly ciirvetl traiisveise line of tlie m m e shape arid relatioilships as t h e n o d d line of cicadas, and appweiitly clividiiig off a inon8 cori.rceous basal portion.

In the nymphs of :dl recent Cic:didE examined the wing par1 itsrlf shows n T ery clistinct riotla1 line in the apical third, dividing off a, very much thiciter basal t w o thirds. ‘Yhis condition appeitrs strikiiigly Heteropterous.

S o nirrclr for the facts. Tlieir significance we believe with HorL 6th atid Mon!tori to he great. Both tliese writers consider the iioclal line homologous with t h a t sepmating corium from

402 DR. 3. G . 'MYERS OX THE

meinhrfine in the Hetei-optera. W e have discussecl i ts possibly priniitire character throughout the order in a later section tle\oterl to pliylogcny. Here we wonld give reasons for coii- sitleriiig it a Iiiglily piiiiiitive clisrncter in the C i c d i d s :-

( I ) lt reaches its greatest development among adult cicadas i n f 'et t iprctci , ~ h i c l i in venation, head-structure, absence of somitl-orc:ms, and in othei cliaracters is the most priniitive exi<tiiig cic:icla.

(2) I t shovs an intermediate condition in such less primitive forn ix :I\ Cl~,ottosaa arid other Tettigadins.

( 3 ) It i b least, developed in those cicadas which are the most higlily evolx ed in other directions, notably in clevelopmeiit of the souritl-oigRiis ancl their accessories.

(4) I t i5 liiglily tlevelopetl arid strikingly Heteropteroid in the Iiyinlphs of even tlie most modern cicatlas, and in all of such that we 11:ive exaininetl.

( 5 ) It definitely occurs in the most cicada-like (Tillyard) all tlic pi e-Cretzceona fossils-the Pakeontinida.

(6) It i x tlefinitely present in aZ1 living cicadas knomn, and tiici.efoi-e iepreserits a definite tendency of the cicada stem.

v. The %iny-cozcpli?ty Apparatus. !rile wing-coupling arrangements are simple in the extreme.

A recurved flange on the dsrsal. surface of the median part of tlie cost:il border, liiiicl-wing, hooks in a recurved flange on the ventral surface of tlie hind-border of the tegmen. The hind-wing flange is strengthened by the conjoined stem of c! + Sc + R 2 + 3 (text- fig. 51).

e. ABDOMEX AND ITS APPEXDAGXS.

u. Gemwal. 'L'CXA distinct segments itre recogiiizable in the cicada abdomen

in botli sexes, and, in addition, posterior. to the tenth. are t w o successive parts of the anal '' segment,'' whicli rnay perliaps be interpreted as segrnent XI. and a telsori respectively, a s Hansen (t ixi~sl , 1902) suggests.

Segnieiits 1. i ~ n d II. are modified extremely in tlie service of hearing ancl sound-production in the male, arid of the former function :done in tlie female. They will be considered ill greater detail when we come t o describe the organs concerned. In both sexes, segments IX. and following are devoted largely t o reproductive purposes, ancl will be described in connection with the external genitalia.

The tergites of the ordinary abdoniinal segments (text-figs. 11, 16) are greatly developed and strongly arched round the ventral surface. The sternites, bearing the 5th to 9th spiracles, a re commensurately restricted.

MORPHOLOGY O F THE CICADIDB. 403

There has been consitlevable discussion with regard to the lateral regions and as t o the presence or absence of abdominal pleurites. Hltnsen (1902, p. 215) takes a somewhat broad band lying between tergite aiid sternite to be the pleuion. This consists of two pal ts-extrinnlly (dorsally) a conspicuous chitinous plate, nhich, except in swollen abdomens like that of Cpstosoma, IS separated from the tergite by R very narrow, thin, marginal uidmbi:ine j and internally (ventrally) by a distinct, narrow, thin inembiane between plate c~ncl sternite, again except in Cystosoma. Heymoris (189‘3) gives v‘rluable embrq ological evidence. R e finds (p. 422) in tlie einbrj o very distinct and Heteropteroid i”ergitinulsfe, which axe passed on to the nymph and appear to be foriiied partly of tergite and partly of paratergite. They dis- appear in the adult, or rather become plates which are sepnrated from tlie sternite by a sutuie, while laterally they reach the slinrp body-edge (p. 424). These correspond to our under-arched part of the teigite, a n d are seen in text-fig. 11. Heymons (pp. 377, 4 i7) denies entirelythat special pleurites are present in

Text-figure 31.

~a~- i i te ta , f in*~nosa (Germ.). J f d e : evteriial view of left lower pygoplioral process (aborted genital e t j l e of Muir).

any Hemipterons ahdonien. H e finds that i n embryonic development each sterriite consists of three plates, of which he calls tlie two laterd ones parctstemites. These are represented in the acliilt cicadas at most by the “ a n tlas Stigma angrenzende Partie ” of the ventral plate (pp. 377,423). Neither paratergites nor parasternites are pleural in origin, though Verhoeff (1893) citlied them respectively “ obere Pleuren ” and ‘‘ unteren Pleuren ” in various other Heniiptera.

Vogel (1923), as we shall see in the description of sound and hearing-organs, recognizes quite a. considerable developnient of the paratorgites ancl pmrsternites-more than we can follow.

Doering (1922, pls. 59, 62, p. 558) shows in the abdomen of the Cercopicl, Lepyronia, large and distinct “ pleura ” which seem to correspond with most of the lateral and ventral part of t h e tergite. It is possible she lilts used the tern1 only in the topo- graphical sense.

Berlese (1909) figures no abdominal pleural structures in any insect, and mentions (p. 255) as the acme of complexity Lacaze- Duthier’s epimerite from the tergite and episternite from t h e

404 DE. J. C. NYG1tS OX THE

sternite, evidently corresponding \T itEi Hcymons’s paratergite and para s t eriii t e .

Comstock (1925, p. 75) states that a n abdominal segment consists typically of a tergurn and a sternum united by lateial coiijunctivze. Sonletiines there are one or two small sclerites in tlir lateral region which are probably rediiced pleura.

lmrvis (1925, p. 41) states that the abdominal phz ra axe meinbrnnous and iisu:iliy without differentiated scleiites.

W e are theirfore justified in interpxeting the abdominal elements iu cicada as a strongly-developed over-arclled tergite meeting an entiiely veutrxl steriiite, which beam the spiracle.

T i b i c ~ n chToronzera w k . I \ lak : lateral 1 iew ofcntirt. Rnd segment.

X., tel.t;i :~bdomirial segnreiit; dm., right mtmbcr of pair of dorsal muscles ; rm., right ineniber of Imir of ventml muscles; u., uncus of Ainericair taxonomists.

It is true that there is : i n irregul:ti,ly rect:mgula,t area at the side of each stelmite, market1 illdistinctly by folds ; but the spiracle i s definitely in the niaiu body of the sternite (text-figs. 11, 21). An internal view is seen in text-fig. 23 .

The cliief endoskeletal structui.es of the nlvdoiiien are the strong pegs fount1 in t h e latero-ventrid portioiiq of the tergites and sbown i i i text-fig;. 23. The structure wliicli gives support t o the tyrnbal-muscles in the male, and is regarded by many R S the furc:i. of t h e first or of the second alxlominal segment, we shall see later is not endoske1et:Ll a t a l l , but merely the modified ventml wall of tlie segment.

B. Ge?Citalia. Whatever. be the nuinher of :r.’oclo~iiin:i I segments admitted, we

have seen tliat the lXth and succeetliiig ones in both sexes are

V0I:PHOLOGY OF I’IIC I’ICADIDB. 405

gueatlv riiorlirietl eitlier directly or iiitllrectly for reproductive piu imhe5. The V I I t l i :inti V I I l t l i a l e d s o soniewhat nlteietl. Altliougii. :is n e s1i:ill see later, Xl i \ tot l r tlescribed copulation, I t rein iiiicvl for &.EalpJglii (1687) aud Re<iuiiiur (1740) t o describe i n ‘my detail the o i g ~ ~ t i s coricerr~ed.

1 lie descriptions wliicli follow :we I i n b e t l on ~lieZunipsrtZtc~ hpp. r ,

i. X a l e Genitalia. L h e ui;ile goiiitnli;~, of Cicatlitla: :IS eiiil>ll:isize~l I 9 7 Kru*lr:~\v a.ncl

Mnir ( I 022) are v ~ i y tii Tlie VIItli steriiitc? is 1:rrge :ind

charact,ei,. Whetlier t ha extension represents a development of tlie YITth coxites is not; known. The po rior borclei. is of ten oinargiiiate in tlie middle, :lilt1 thus :iffords soine slight evidence of primitive t1u:ility. The Imckwitrd ert,ensioii covers t h e base of tlie V I T l t h sternite (hypnndrium) as a crescentic free flap.

Tile V I l I t l i teugite is Ial,ge a n d carved dowii 1i~tero-cetitra.lly

r ,

inch. I,”otlllcetl k,:I,ckwnrci (t.ext g. 35), i t s s1i:ipe being it good tasoilotriic

‘re x t- fig Lire 3 3 .

,Uelampsalta c i n , p l a t a . KO13 preparation of anal segment. i., intersegiiieiital meuibraiie.

so as almost to forni it complete ring. The V I I l t l i sterriite is large i ~ i i ( 1 boat-sliaped i ~ n d constitutes t h e Iiypaiiduiuni (text- jig. 35). Tliere is sonic: evideiice--sliglit hilob;i.tiou at tlie tip- tlint tile fused coxites enter into t h e composition of t h e Irypan- drium. 111 all other liiiciienorrliyricl~:~ these coxites ai’e iiicorporatecl into t h e pygoplior (lX,). 111 the trough of the liyparitlriuni t h e pygoplioi lies at rest. Fuiiklionser ( 1917) tigures a siirii1:w plute in &leinbr;acid~, anrl corihitleus i t “ :ippareiitly t h e steriinin of tlie nirit,li seguieiit.” Newell ( I 918) would call i t tlie I X t h sternite in cicada, but there is no evidence for tliis ant1 inucli t o tlie coiitmiy (text-fig. 35).

The pygoplior is ;t ~ti~oi :gr i~-cl i i t inize~ iiiore or less cylindrical case suruouiitliiig the teriiiiriatioii of t h e g u t and tlie genitalia. I he wi~ole of t h e dorsal and la.teral portions a r e formed froni the IXth tergitr. The ventral sui,face is membranous aiitl of un- certiiiii origin. ‘Ulie lateral margin h w s on each side it process, entirely non-articulate, which Muir and Kersliaw homologize

This coriclition is peculiar t o the Cicndidr-e.

r 1

406 DR. J . G . MYERS ON THE

with tlie otherwise entirely lnclring genital styles (text-figs. 31, 35). Singh-Prutbi does iiot agree Tith this hoinology (1925), and me tiunk i t rather doubtful. True genital styles arc present i r i Z‘ettiprvctu (Wuir, i ? ~ Zitt. ; Singti-Pruthi, 1925).

111 repose no portion of the pygoplior extends beyond tlie hypnt l r ium terminally, lorit the teq$ spiiie--a dorso-cnnrlal pi ojection of tlie IXtEi tergite-ends tlie c1ors:d line of t he ahloinen. This teigwl spine. wlricli is the “irieclian d o r d spine” of Woodworth (1888), varies specifically, and is valuable in taxonomy I.

T)istnlly the pyqoplior bears the anal segment or anal tube, ni:irle a p chietiy of the X t h tergite. The Xtli qegment is produced ventrally into a inore or les3 wide plate, extending in

Text-figure 34.

Tibicen chloromera. Internal view of left half of male pygophor. or)., left half of basal opening of pygophor; ej., ejaculatory duct; pe., periandrial

thickenings (busal plates of Singh-Fruth) ; ys., Muir’s aborted genital i;tyle ; md., redeagus ; t., tendon for left member of pair of powerfnl muscles.

Melanzpsaltrc cinguluta (text-fig. 35) directly cauclad, but in dL nmta ~ i i d its relatives directly ventrad. Proxinially to th i s again tlie edge of tire anal segment hears two downwardly-directed, stout, curved, non-articulate hooks which I call copulatory c1:rspers (text-6g. 35). These may be cerci-organs generally considered absent from the entire order, Hemiptera ; they a re appendages of the X t h segment, and thus in cicada the most distal, but they have lost all articulation. Cmmptoii (1922, pl. 3 . fig. 9) calls them ‘‘ sargouopods (cerci? ).” Newell labels them cerci, hut notes that in no Herniptern are these organs segmented (1918, p. 125). Berlese (1909, fig. 347) applies t he term cercus

* Tlie term y?Jqophor is preferable to pygofer-a 11) brid often encountered-and The dipterological still more so to the plural form of the latter, frequently used.

term hypopygmm is equivalent.

MORPHOLOGY O F T E E CICADIDE. 407

i n tlie female t o the epiproct, presently t o he described, and in the male (fig. 399) to two sinnller lateral pieces at their base. The copulatory hooks protect the wdeagus, which peeps out between them, and they thus take the place of the absent genital styles. In Z'ibicen ant1 related genera the copulatorv hooks a re often fused i u the middle line t o form the uncus 2 American taxononlists (text-fig. 32, u.). This structure when single, a s in T i b i c e x ch~0?.07?2ei~6, shows a deep o.roove, proximally. in c tudal view, marking the line of fusion. bThe base of each copnlatory hook ciirves round and merely meets t ha t of the opposite side, forming an ;ipertiire through which the mleagris passes to the euterioi. This is a much niore specialized Xtli segment than that of ilIdunzpsultcc ; yet tlie zseclengiis is very iiiiich simpler-

Text-figure 35.

\

I

. . . a

Jrelanzpsnlta cingulata. ICOII preparation, partially sectioned. VII.-S., abdominal segments : sp. 10, last spiracle (position only indicated).

(For esplanstioii of other lettering see text-fig. 34.)

possibly by correla.ted reduction. In ilfelanzpsulta cuesda tlie work of the unci is is perfomied by a strongly-curved plate which looks very much like one, but is distal to the true copulatory hooks which lie beneath i t , and is thus hoinologoue with the directly caudal extension of segment X. already described in JL cinguluta (text-fig. 35) . Both this and the true copulatory hooks are shown distinctly iu lateral view in text-figs. 33 and 36 of cingzclata and of sericea respectively. The condition in the latter suggests t ha t the second projection may possibly pertain to an X l t h segment. The modification of the Xth segment occurs in no other Hemiptera (Singh-Prutlii).

Beyond the anus and the X t h segment is a dorsal lamina or epiproct (text-fig. 36, ep.) and a ventral one or anal style (as.).

403 DR. J. G . MYERS OX THE

The for~i ie r is the tclson of Doering (1922) in the Cercopitize. A t blie h s e of these on each side is LL rouncletl, sometimes shining bl;ic!r p h t e \vlricli Berlese (1909, fig. 399) labels cercus, but mliich is inore coiicitivnbly a podical plate from which tlie cercus has been lost.

&lecigrcs.--ln Jfelccnzpscclta this consists of a stout, basal, b i loh tc imlb, the per%andri?cnz, and t h e e long distal processes surrouiidiug :i,rid more or less p~rallel to the penis itself. Muir arid Iietsjhaw (1922, p. 205) ca.11 the distrtl portion of the tedeagus the p i s i s , but it would seem better to restrict the term adeagus

Test-figure 36.

illelrr~~z~~sulta sericsa. Male : anal segmeiit complete, soft parts stippled. ep., epiproct ; as., anal stj-le ; i., iiiterseginental membrane.

t,o tire actual sheath. Of the three arms of tlie tedeagus, two are laterd aid the third uiedian ~ i i t l he;tririg d i s t d g the orifice of the penis.

The pei.iniitlriuni arises as a tliickeiiiiig in tlie body-wall between the IXtli a i id Xth segiiients. These t,hickenin,vs(~~oJiclZo of Yerlese) are cdled busul plates I)y Bingli-Pmtkii (1925, p. 136), a,ud considered of very great inorphological significance. He wou!d homologize tlierrr with certaiii distinct sclerites near the btwes of t h e zdeagus mid the genital styles in such other Horlroptera ~1s Cicatlellide. This Iioiriology would seein to be entirely fancifiil. Singti-Prutlii states that " basnl plates " are

bIORPIlOLOGII O F TIlE C:ICADIDB. 4U9

present in Cicxdina Dist., Gmmiinze Dist., a n d some TibiciniilE, but, :we a.bsent in t h e rest of the latter. I n such forms as l ' ib icen the t,hickenings of t h e pei~iiinclriui~i a r e cri%ainly very strongly developed (text-fig. 34, pe . ) . but i t woultl appear tlia,t no hard-and- fast line can I)e drawn. On this hiisis Sirigh-Prvthi considers t11a.t t h e CicadiLs of t h e snbfnaiily P1a . typ lenr in~ (Gicadinle Dist.), usually believed on other counts t o lie t h e most highly evolved of t h e family, exhibit t h e most primitive conditions.

I n spite of its frequent complexity the Cicarlid Lcdeagus may be coilsidered relatively primitive. It shows little of t h a t iiira~gina- tiori of t h e tlistnl in to the nroxiriial nortion characteristic of nlanv other Herniptera-e. 9. ever, t r u e t h a t Apgm

Fulgoroidea a n d Heteropte1.a. It is, h o x - (1887) l ln< described quit? a conililicated

Text - fig tire 3 7.

__-

eritloionle in t i l e adeagus of Nc~giciduda so1~tenrlecinz, while in most cicadas the whole a l e a g u b occiipies a soinewhat internal positioii, brought about by invagination of the >~iit iaI nreiitbrnne of tlic pygoplior arid of t h e intersegmental nienihrarie between that and segment X.

The chief n-01 keys or1 the genitalia of male Auclienorihj ncha. and incidentally of CicatliriE, have been ~ 2 a I p i g h i (1687), li6nuninr (1740). Dufour (1833), Newel], l Ieyi~ions, Kerslmw ant1 1\lTuir (1922), Muii. (nlany ppers) , LRV son, Singl i -Pmthi (1924, 1926), Doering (1922).

ii. The Pevnrde Genitcclici. 'Clip female genitalia consist essentially of three pairs cf appen-

'i'lie5e make up t h e ovipositor clageh, f r q u e n t l y known as valves.

410 DR. J. G . JlYERS O N THE

and its sheaths. The central or inner pair is fused for the greater part of its length, forming distally a single solid piece (text-fig. 30, nzp.) with sharp atrongly-cbitinizecl apex. Tlie pygn- phor is not unlike that of the male iu shape (text-fig. 37, 1X. t . ) , with a longer and niore tubular anal segment which lacks the armature of that of the male, but is otherwise es~ent~ially similar.

The central piece formed by fusion of the inner pair acts as guide-piece for the outer or proximal pair which partially en- closes it (text-fig. 30,Z.). The three pieces are welrled into a functionally single weapon by means of a t least t h e e pairs of

Text-figures 38-47.

P 38

c

Veiitrsl 1 iew of ovipositor tip, left half, of qpecies of Xelavzpal ta : cingulatu ( 2 specimens), s t ~ e p i t a n s (Kirk.), ci-uentata (F.), Zeptoazera, sericea, mzcta,

, f idiginosu Myers, and ~nzcta mrs. subalp ina (Hnds.) and czctora (Wk.).

interlocking grooves m c l ridges, well sliomn by Marlatt in cross- section (1 907, fig. 37). Such interlocking, wliile effestually preventing 1atera.l movement of individna.1 pieces, allows a.nd indeetl f:i.cilitatee. longitndind sliding of the ventral or outer pair on the iniddle piece, the tip of which is sharp and hard. The apices of the ventral or hternl pieces (text-fig. 30, I.) beyond the t ip of their infolded portion clasping the middle piece are likewise blxclily, heavily chitinized a,nd furnished with a number of oblique cutting-edges. These a re the effective instruments of perforation. Lawson was the first to figure these in deta,il for a

MORPHOLOGY OF THE CICADIDB. 41 1

number of species (1920, pls. 24, 36) and to claim that they are of considerable value in taxonomy. Nothing is more needed in cicada systematics to-day tlinn some new character intlepentlent, of male characters, but ou r experiences in il.llampsalta (text- figs. 38-47) do not lead us t o hope for very much fiom these as characters for specific separ ation.

While the prosinial portion of the whole ovipositor is protected Iaternlly if riot ventrally by the pygophor, its distal part is en- sheathed by the third pair of appendages, which are less strongly chitinized, apically roundetl, and usually haix y (text-figs. 30,37, s.).

Attachments of Ovipositor.--The lateral pieces arise from the VII I th sternum (text-fig. 37, VIII. s.), which is represented by two triangular sclerrtes largely hidden by the VIIth, which, as shown in text-fig. 11, abuts largely on the base of the ovipositor. The dorsal basal angle (outer b. a. of Muir and Kershaw, 1922, in

Text-figure 48.

hmb

IWelainpsalta iiiuta. Right tegmen. amfi., ambient veil:.

(S.H.-Veuation for text-figures 48-59. The usual abbreviations of tlie Comstock- Needham notat,ion employed.)

Cercopirlze) of the lateral pieces is joined to the posterior basal angle of the I X t h tergite as shown in text-fig. 30. The I X t h sternum, in SO far as it is chitinizecl, consists of alsrge, somewhat elongate, boat-shapetl sclerite or plate situated on each side of the mid-ventral line and homologized with the orthopteroicl valvifer. Proxinmlly this gives rise to the iniddle piece, formed by the fusion of the inner pair of appendages, which are perfectly separate for some dista.nce from their origin. Distally the I X t h sternal sclerites are continued by a imembranous area, shown stippled in text-fig. 30, into the two hairy appendages (s.) forming tlie ovipositor sheat,h. Berlese (190'3: pp. 302,303, fig. 347) would homologize the latter with the prostili of Orthoptera.

The vnrious names applied in taxonomic a,nd morphological literature to tlie t h e e pairs of gonapophyses comprised in the ovipositor arid i ts sheaths are so confusing tha t we are impelled t o siibniit a table of thein.

412 DLl. J . G. MYERS OS ‘THE

g.’=snw-valves (t,ext-fig. 30, Z.), ventral valves (Tillyard, Doering), anterior,

g.2=niiddle piece (text-fig. 30, mp.), inner valves (Tillyard), niediaii

g.:j=slieatlia (teat-fig. 30, s.), dorsal valves (Tillyard), posterior processes

outer, o r ventral processes (Muir aiid I<ersliaw).

processes (XIuir and Kershaw), dorsnl valves (Uoering).

(Jluir and Kershaw), lateral valves (Doering).

The first writer t o concern himself with the structure of tlir

‘’ pariimf [CicndEJ in aruis cessaritibus, excavnntes asperitate przeacutn, quain pnrte liabent posteriore. . . . ” Hist. ccnz’m. ; Gnza, lib. v. cn,p. 30.

lCZalpiglii (1687) gives a ventral view of the ovipositor (ii. p. 38, tab. xi. f . 2) showing some detail, and then proceeds t’o describe i t as the male genitalia, thus :-

‘( I n Ctcnclis etiam fceminis, eadern pudendi conforniatio imuiri ventris occnp:Lt : in his penis A binis c0nsts.t assibus, quorum extreniitas, pluribus eminentiis aspera, glnndem B con- stituit ; custoditnr autem vagina C, q u a e t ipsa in binas aperitur partes non longe ab an0 D.” Yet on an earlier pzge’(i. p. 129, fig. 73) he writes:- ‘‘ In Cicadis (73) insignis magniti[clinis terebra. extat, qunin olim pro pene, i ta cleceptus, delineavi. H u j u s structora mirani NatiirE s:tg;witaterri pa.tefa,cit.”

Then follows a good a n d detailed description of tlie ovipositor ; but :I. passage on p. 131 still leaves i t doubtful whether lie really lr ne EJ t l I e in a1 e g en i tal ia .

These latter were considered with admirable detail arid figured with much clearness by Re‘aumur (1740), whose description of the ovipositor, more rnnsterlg than tha t of his gi-eibt predecessor. bec:amo the reference :wxount, for subsequent en tonlologists almost to tlie present (lay.

Later workers 011 the structure and lioiiiology of tlie female genitalia. of A.ucheno~rh3.nclia in general or of Cica.didse in par- ticulnr are Doyere (1 837a), Hyat t (1896), aiid Heymons, VerhoefY, Kershxw and Muir (1922).

ovipositor w:xs Aristotle, who merely notes :-

iii. JIonzologies of the Genitalia. Korsha.w and Rluir (1!)22) would homologize the geiiital

appendages in the two sexes. They firid the more general coii- rlition in H.omoptera. to be as follows. (For convenience iu reference we ha.ve coil:i.ted the synonymy) :-

g.’=;niterior goiiapoph! ses =:ippcridages of VIII . =hypovalvi*, (CYnmpton).

=subgenital plate (Siiigli.Prnt1!i). =genital plate (Kershaw & Muir).

MORPHOLOGY O F THE CICADIDB.

g.?=median gonapophyses =appendngsn of I X . =adeagnn of male. =iniddle piece of ovipositor.

g.3=posterior goiiapopliyses=Koirocosites of IX. (Tillyard).

3 3faIe. =genital styles (K. C Muir). =parameres (Singh.Pruthij. =ovipositor sheaths.

413

I n the cicatlid female all three pairs are well represented : in the rnale g.’ are apparently I:dcing, though perhaps fused in the hypxndrium, wliile g.’ are prncticaily aborted save i n Tetti- gcoctffi.

Several writers, notably Doering (1922) and Singh-Prntbi, have questioned this homology on morphological arid embryological grounds, and Muir (1925) has reviewed tlie evidence anew.

Text-figure 49.

Chonosia ci-assipennis (Wk.). Tegrnen of aberrant specimen, with abnormal Cu 1.

Tillyaril, in his new general work (1926), agrees tha t a complete homology exists between the two sexes.

While most writers agree tha t the posterior two pairs of gona- popliyses-tlie adeagns ant1 genital styles of the inale arid tlie inner processes arid onter sheaths of tlie female-are honiologous in the two sexes, Keishnw S: Muir a r i d Tillyard would appear t o be alorie in considering tlie anterior pair SO also. The forrner have brought forward very convincing evidence for their view. As, however, the qnestion can be settled only by renewed embryological work and by comparative studies not only in Heiniptera but in other orders, i t is outside the scope of this paper and need concern i ib no further here.

( 8 ) INTERNAL ANATOMY. Our alcohol material heing scanty, we have been compelled to

ilse niost of it for the elucidation of the digestive system, and, with reference t o the other organa, to make what incidental observations we could arid collate previous references.

PROC. ZOOL. S0c.-1928, NO. XXVIII. 28

414 DW. J. G . MYIGRS O X THE

a. NERVOUS SYSTEM. u. Genernl.

The chief writers to concerii themselves with the ner:7ous system and sense-organs of Cicadidae, either especially or inci- dentsally, were Meckel (1818) and Dufour (1833), who laid the foiindntion of so marly branches of Hemipterous anatomy, Brandt (1878), Rossi (1879-1880), Binet (1894), Rerlese (1909), Swinton (1877b, 1879- 1880), and Vogel (1922, 1923); Will (1840), Gre‘nacher (1879).

Meckel descrihetl in ’I’ibicen pleheiu the brain and 4 “ TCnoten,” the last I a i p r ,

Dufour (pp. 264-266, separate pagination) described in Cicadu omai L. a cephalic ganglion and two thoracic ganglia. He noticed that the former was produced by a fusion of two hemi- splieroid lobes, the fissure sepwating which WRS only snperficial.

Text-figure 50.

R +M

Tettigarcta eriitita. Tegmen. as., axillmy sclerites; ax., sxillary cord.

(N.U.-Text-figs. 48-22 me of tliffererlt magnifications.)

The anterior part gives h e to an optic nerve on each sitle. This nerve, pyramidal 01- shortly, thickly club-shaped, embi-aces the ocular bulb. Anteriorly ariaes a trifid nerve of wliich the three branches go to the ocelli. The esophageal ring gives rise t o :L pair of neives for the muscles moving the hend. The thoracic ganglia, far from being separate :md distinct as in ,Yepa, are tiearly fused into one, :ts in the “ Geocorises.” With difficulty one traces the light dernarcation of :in interior ganglion. The ensemble of the two gimgli;t forma an oblong body, deeply situated beneath the ni~~scle-niasses which fill the lower wnllof the tliorax. The anterior ganglion gives rise to four pairs of principal nerves, and t he posterior to six. The two nerve-cords, towards tlieir origin, are contiguous as if adherent, but in the abdominal cavity they sepnrate before finally dividing.

Such in brief is Dufour’s century-old description, and it is

MORPHOLOGY O F THE CICAUIDE. 415

snrprising bow little from the gross anatomical viewpoint can be added thereto to-day. Text-fig. 70 shows certain rather striking differences in Melanzpsalta seimicea from the condition described by Dufour in Cicada orni. If these be coilfirmed they would go to show that there is considerable diversity in the family, and that Melanzpscclta is considerably less specialized than orni in the development of the nervous system. Instead of the two thoracic ghnglionic masses distinguished with rlificrilty in orni, there are i n sericea three, the foremost of which is quite distinct. Dofour makes no melition of a sub-mophageal ganglion, which he probably confused with the brain itself.

Remarkably little is known about tlie general nervous system of any Hemiptera, and there is but scanty niaterial for comparison. It would appear, however, that the Cicdicke are

Text-figure 51. C U l L

s? ib icPJL ehloromera. Wing-conplirig apparatns-part of hind-border of tegnieii and fore-border of hind wing, in dorsal view.

uf. 1, downfold of teginen (viewed througli membrane of wing) ; tuf. 2, upfold of hind wing.

.corisider:thly specialized so far as the nervous system is concerned, although less so in some respects than tlie Cicadellida (Jassoidea), in which, as for instance in Ur~culaaephnla, Cogan (1916, pl. 22. fig. 32) shows the whole central gnnglionic system as practically one elongate mass with a small aperture for the cesophagus.

Berlese fin& that in some Coccids and Heteroptera the sub- esophageal ganglion is fused with the thoracic mass.

Binet (1894) has supplied perhaps the most thorough study of the subintestinal nervous system in cicadas (Cicada o m i ) . H e remarks first of all (p. 486) :-

$ 6 p:i,rmi tous les Insectes que nous avons 6tudiBs, nous avons trouv4 les cellules nerveuses les plus considerables chez la

28*

416 DR. J. G . MYERS ON T€UC

cjgale; on trouve dans l a r4gion abdoniinale des centres rierveux cle cet Insecte deux cellules g4antes niesuiant 150 p snivant leor plus giand diamktre.” K n t Binet‘s greatest discovery (pp. 542, 543) concexns t h e

abclornirial ganglia, which, though fused wi th t h e last thoracic mass, a re nevertheless distinguished in sections by t h e absence of craral lobes, correlatecl with t h e absence of legs in the corresponding segments. The first abdonrinal gqnglion diEers from t h e sncceeding ones in possessing a sv elling of t h e dorsal lobe. This swelling is formed by two very distinct lobes, wbiclr are superadded to t h e dorsal lobe of t h e ganglion. Each of them occupies tlie externo-superior position, and they are separated by

Text-figure 5 2 . 11 5, c

‘ - - - ! _ _ _ _ _ _ _ 7 ._ _ .

M 3 +.& ;-,p---?< ’. . - ~ -J - . . . . -‘

LWeeln7~7psaZtn ma&. Part of right trgmen, viewed doisally. I$., node; j . , joints or breaks in t h e veins.

a deep indentat ion where t h e great ganglionic cells accntxuIate. The two lobes a re situated i n f ront of a ganglionic cell of exceptional size, which lies a t t h e level where t h e crural nerves enter t h e central nervow system. A longitudinal section shows tllat each of t h e new lobes is ~ i t ~ u a t e d jus t behind t h e car- responding nletathoimcic crur:il lohe. The cocnl lobes, as Binet Cnlls them, are intinlately united wit11 t h e dorsal lobe of tile ganglion, which. is essentially motor. They have no ad2ierence t o t h e ventral lobe, froni which they remain dis tant for 811 their extent. Thus they differ from t h e crural lobes, which, situated laterally, in relation a t once with tlie sensory (ventral) a n d nlotor (dorsal) lobe, a r e both sensory and motor. The vocal lobe 6 ‘ pnrAit e t re uniyueinerit done‘ d c fonctions inotrices.”

It will be interesting to s tudy the relations of t h e ailditory nerve, discovered since Binet’s time, with t h e abdominal ganglion in q u ~ s t i o n . Vogel (1023) describes it as hranching from the abdominal s t rand, apparently i n t h e I I n d segment. Our materia] at present fails t o settle this point.

MOILPHOLOGY 06 I'HE CICADIDB. 417

We have examined the gross anatomy of the nervous system in imsuitably-preserved niaterial of -Ilela.n~palta wuiffi, M. sericea, and Ccirinetc6 for7nosa. The brain is esconced on the second swelling of the tligestive canal, jnst behind the dorsal dilator muscles of this organ. It is consicleiably wider than long (text- fig. 70, 6.). The optic nerves are huge and long, and corpora perZic7zculota lacking. Rerlese notices that the protocerebral lobes are small and the others still smaller. The ocellar nerves are as described by Dufour-their branching from the common stem does not occur until just below the ocelli themselves. Rerlese figures the brain of l'ibicen plebeia (text-fig. 697), a section of the procerebral mass in the snme insect (text-fig. 694), and also a section of its whole brain (Tav. .I-1, ii.).

Text-figure 53.

Tettigareta crinita. Riglit liiiid wing.

The esophageal connectives (text-fig. 70, c.) are stout arid rather long-in iVekcntpsa~ta less so than in plebeic6, ns figured by I3erlese. The subcesophageal ganglion is rounded, joined by long, stout, well-separated cords t o the 6rst thoracic ganglionic mass, which lies largely in the prothorax. This has two short, very stout connectives to the second thoracic mass, which is much longer than broad and shows signs of two-fold origin. It lies wholly within the mesothorax and. in fact, does not reach the niesophragma. Posteriorly it passes into a superficially single cord which splits into two a s i t enters the abdomen. From the sbantlpoint of gross anatomy the abdominal ganglia fused in the second mass are not to be distinguished.

The sympathetic nervous system has not been studied in Cicadidz nor related families.

F. E y e s a?id Ocelli. The compound eyes have been studied in Cicada ormi L. by

Will (1840) and in Cicada. gyossa. (?) by Grenacher (1879). According to the former, each eye in OWL^ has 11,600 ommatidia (p. 11). Grenacher (p. 96) finds the eyes are of the eucone type, i. e., each visual element coiitains a true crystalline cone, in front

4 l Q DR. J. G. MYERS ON THE

of which are the nuclei of the cone-cells. The retinnla is formed from eight distinct elements, and the crystalline cone5 are very well developed.

The compound eyes iu Grenacller’s opinion approximate most closely to the Hymenopterous type and differ ‘( sehr betrachlich ” from t!he Heteiopterous-a fact which need not occasion surprise when one considers how largely C‘icadidz appear t o depend upon their eyes.

Their habit of dodging like n squirrel behind a branch, keeping it ever between theinselves and the observer, is very amusing, and is shared also by certain Heteroptera, notably mirids. That the compound eyes are the cbief organs involved is suggested by the absence of ocelli in &firid%.

s c +R cu-

Text-figure 54.

Nelampsalta mutn. liight hind wing.

The ocelli are three in number and markedly red in colour. Berlese (1909, p. 672, fig. 840) has studied in some detail those of T’ibicem pbheia, while Link in the same year (pp, 354-356, text-fig. 0, Taf. 24. fig. 27) gives a more thorough-going account in “ Cicuda concivzna L.” (= ? C’icadatro atra ( O h . ). The most striking feature i s the presence of pigment-cells between the sense-cells-a characteristic of Auchenorrhyncha. Link shows tha t these red pigment-cells are derived from the corneagen layer. Berlese (1909, p. 672), however, disagrees. The pigment is in the form of red granules, filling the cells.

Link erroneously considered the ‘. Gattung Cicada ” as t h e only one in the Humoptera furnished with three ocelli.

W e have seen that the ocellar nerves are bound in a common stem to near the ocelli. Link goes further and finds that the branch then proceeding to the median ocellus is really double, whence he speculates whether t h condition is secondary, or denotes fusion from an original pair. Hymenoptera and

MORPHOLOGY OF T H E CICADIDB. 41s

Odonata-notably insects with well-developed visual powers- share this arrangement with the cicaclas.

Link repeats the well-known liypotheses that the function of the ocelli may be connected with the need for sudden inove- ments-since they are well developed in niost jumping insects-- or with orientation, as suggested by their position.

I n an insect like a cicada, with the head and prothorax almost immovably fixed to the rest of the body, the ocelli would certainly seem to complete the visual equipment 60 far as direction i s concerned. The field of the great conipound eyes is largely lateral j the paired ocelli look directly upward, while the median one is often on an eminence which directs i t forward.

Whatever be the respective functions of this rather complicated viaual apparatus, n o one who lias collected cicadas will question the ability of the insects to use it very effectively.

Text-figure 55.

SC +R r4

Tibieen chloromera. Base of right tegmen.

y . Auditory Organs. Tho supposed absence of auditory organs in the CicaclidE was

long one of the chief arguments against any sexual significance in the song. To Swinton (1877 b, 1879, 1880) must be given t h e credit for discovering a n organ to fill this lack. Unfortunately Swinton wrote in such an involved style, euphuistic, highly allusive, and abounding in long irrelevant discussions, tha t he effectually disguised the solid scientific contribution often contained in his writings. I n reading him one had always the impression of vapourising dilettantism ; one met never without surprise every additional citation indicating tha t he knew thoroughly the literature of his subject. One does not expect an epocbmaking discovery among the amiable ramblings of a n undated volume with such a title as ' Insect Variety: its propa- gation and distribution.'

420 DR. J. G . MYEBS ON THE

It is true tha t Swinton reported very briefly his investigations also in a scientific periodical (1879) ; hut, for all that , they were completely ignored by all subsequent workers until practically the present day. The masterly and detailed description of cicada auditory organs by Vogel in 1923 involved their discovery anew, and it was not until Vogel’s work was ell on the way to corn- pletion tha t he found Swinton’s long previous account.

The first detailed descriptions of cicada sound-producing * organs had niade knowir the mirror -an extremely thin and

delicate, beautifully iridescent membrane closing the cavity of the sound-apparatus posteriorly. I n spite of a t least some experiments to indicate the contrary, almost every observer since and including Reaumur lms assumed that the mirrors act as resonators. This will be found in every modern account of cicada sound-organs. Swinton‘s contribution consisted in his recognition of tlie mirror as the t,ympanum of an auditory organ.

Text-figure 56.

Lem6ejafatiZoqua (St%l). Apical half of right tegmen. amb., ambient vein.

Swinton was purely an amateur, and could not ‘have elucidated the microscopic structure of the chorclontnl organ itself, even had he seen it. H e described, however, the auditory nerve, the thickened line on the tympanum, the spatulate process at its lateral extremity, and tlie external appearance of the auditory capsule.

To Vogel alone we owe a complete account of this remarkable organ and its accessory structures. The mirror is seen a t M (text-figs. 13. 17, 18, 19, 20, 27). It is an extremely fine skin, according to Vogel, only 5 p. thick in the middle, in two species of Ne2umpsultn studied by him. As to its origin, that is so wrapped up with the development of the sound-organs that we must consider them together when the l ~ t t e r are debcribed. For the present we content ourselves with a brief account of the sound-organ a s it occurs. I n the lateral part of each tympanum is ,z dark thickened line (text-fig. 19,p.) which leads csntiewards but never reaches the middle. From the broadened lateral end of tlie thickening arises a spatulate chitinous process, running

DlORPIlOLOGY O F TIIE CICAUIDB. 483

obliquely into the auditory capsule, where i t serves as an attachment surface for the sense-organ.

l h e auditory capsule is a more or less ‘hemispherical swelling (a.) on the uentro-lateral portion of the I Ind abdomiiial tergite (paratergite, Vogel). The lumen contains I-iEmolymph and blood corpuncles, the last often accumulated in the angles. Where the capsule joins the body-wall, there are outgrowths forming surrounding chitinous rings and making the capsule larger and more nearly spherical (text-figs. 25 , 26). the inner surface of the capsule there remains a larger oval opening, wliicli is covered by thin membrane (according t o Vogel, the wall of the tracheal sac, as he names our rneseriteric sac). Vogel calls this opening the feizestra ovaZis, from analogy with

r ,

Only on the middle of ’

Text-figure 57.

I’yena wmclagascariensis (Dist.). Ilasal part of left tegmpn. am., ampliate precostal area.

the vertebrate ear. On the ventral side the ca.psule coniinunicates with the abdominal cavity by a slit overlaid by the mesenteric sac. This slit leads into one of the grooves formed by the sternum of the I Ind abdominal segment (text-fig. 26).

Tlie actual sense-organ itself is st,retched in the cavity of the auditory capsule, between two spring-like chitinous pieces. One is the spatuhte process from the typanuro, while the other is a n invagination of the outer wall of the capsule, where it a.ppears as a slit in external view (text-figs. 16, 17, 24). The spatulate precess lies in the same plane as the tympanum, from which it arises.

l h e sense-organ sliows all the structure of a chordotonal organ in so far as its sense-cells terminate in the usual rod-like bodies or scolopales, and are stretclied by mems of fibril1a.r differentiated hypoderm cells between two points of the cut,icle. It is distinguished from all hitherto-described chordotonal organs by the enormous number of sense-cells or scolopophores. Schwabe

- 3

422 DX. J. G. MYERS ON THE

found upwards of a 100 in the tympannl sense-organs of Locustids and Gryllids ; the cicada, Me2nnipsaZtu coriuriu, studied by Vogd has about 1500. But the most important distinction shown in cicadas is that the proximal fastening point is differentiated into rz tympanum whose swinging is registered by the sense apparatus. Usually it is the distal one which is thus modified.

Vogel speculates as to whether the scolopophores, in their tremendous numbers, are capable of sound-analysis in a manner analogous t o that of the fibres of Corti. I n i%feZun~psnltu coriaria they vary in length from .2-.31 mm., AS compared with *04-.5 mm. in Man (Helmholtz). H e decides that there would probably be

Text-figure 58.

Me?aelampsalta mzcta. Portion of right teamen to show chief elemelits of nodal line-

only x small range. If it, were demonstrated i t would go farzto explain the great effect of certain sounds on cicadas and their indifference to others, as in Fabre’s classical experiment with the festal cannon, which the cicadas ignored entirely. \

For the histology of the sense-organ itself we must refer to Vogel’s very able paper (1933). There reiliain several accessory strnctures to mention.

The first is n simple dorso-ventral muscle which acts as a temor tympnlzi.

The second is Vogel’s great tracheal sac, which he describes as abutting on the inner side of the sense-orgnn and of the tympanum and acting as a pressure-equaliser, maintaining air -pressure

MORPHOLOGY OF THE CICADIDB. 423

equilibrium on both sides of the tympanum with which he claims that its wall is fused. This “tracheal” sac is .pparently the inesenteric sac which we hope to deal with in n later section. Tt, has been the subject of endless controversy, so c contending that i t is part of the digestive tract nnd others th3t it is part of the tracheal system. W e believe that we have ctnfirmed the work of those who regard i t as mesenteric in origin, ‘ nd we have certainly found no trace of a connection with the tracheal

Text-figure 59.

C P

Chonosia crassipennis. Part of notuni and base of tegmeii of male to sliow the stridulatory orpan.

sa., stridulating area; p., proiiotum; m., iiiesonotum ; e., costa; cs., costal sclerite ; pt., posterior tuberosity of tegmeu ; ax., axillary cord of tegmeii.

system, nor do we believe tha t its wall fuses with the auditory tympanum or mirror. The whole evidence is discussed in the section on the alimentary system.

Wi th regard to the auditory nerve, Swinton (1S79, p. 81) traced it from a thoracic ganglionic niasa to the abdomen and round the tymbal muscle, after which his description becomes obscure. Tlie “acoustic” nerve is said then to form a c‘ ganglion ” tha t “ enters a groove.”

424 DR. J. G . XYERS ON T H E

Accorcling to Vogel the auditory nerve arises in the I Ind abdorninal segment from the two great ventral nerve-strands, and rises, running parallel with the body-wall, i n a chitinous groove dorsally to the sense-organ, where its fibres run one into the base of each sense-cell. In my poorly-preserved material I found a distinct nerve emerging on each side of the last thoracic gnnglionic. mass near the end, and running yarallel to the abdominal cord. I followed i t nearly to ft chitinous ridge leecling up to the auditory capsule, and suspect tha t it is the

Text-figure 60.

a i’arineta for~izosa. Ventral view of dimentnry system, entirely scbematic.

a?., msophagus ; sp., suspensory ligameiit of meseliteric snc; fc., filter-chamber (stonlac111 ; ni., ascending intestine (mid) ; di., descendillg intestine (bind) j m., niesenteric sac ; rs., musciilar rectal aac ; a., anus.

auditory nerve. i t seems very iniprobnble t h t it should arise from the abdoniina.1 strands, as Vogel seems t o state.

In the primitive il’ettigarcta, which lacks all trace of sound- o rpus , I have been unable to find, in the two females available, any signs of an audit,ory ca.psule o r of a tympanum. But the evidenue is not conclusive, since these specimens were rather badly attacked by ants before they came into my possession, and were especially damaged on the basal abdominal segments, which .are, moreover, thiclrly covered with long hair. If, however, suck

M O R P H O L O U Y OF TIIE CICADIDAS. 425

an organ is present, it is decidedly extremely reduced. I have since been able t o examine a i d e of the sdnie species (T. cyiraita Dist,.), thanks to the great lcincliiess of Mrb. F. Muir, and have found a very slight swelling on the rentro-lateral angle of the IInd tergite, b u t no external evidence that this is an auditory CxpS~k.

2. Other Sere/tse-O~*qans. The antennze bear a number of sense organs or, rather,

sensillq usually considered (Redese, 1909) :is olfactory, although 1 nm not aware of any experiinerital evidence 111 snpport of this view. Hansen (1890) \\a\ the first to describe these. The secontl (and of course also the first) segment of the antenrial peduncle lacks these organs entirely j but on t h o untlerside of

Text-figure 61.

Carineta furmosa. Male : dorsal view of anterior portion of meseiiteric sac atid related parts.

m p . , Malpighian tubules. (Other lettering a s in test-tig. 60.)

tlie first and second segments of the fl:igelluirr there is a large nnniber (text-fig. 69). Each is a pit wit11 x blurit conical spike at tlie bottom. Hnnsen distinguished two differeilt kinds-some fairly large, wide, and sli:tl:ow, arid others snialler and deep, the spikes hardly projecting from the orifice. A few of the ~mel le r kind recur on the succeeding segments of the fhgellnm.

i7Idanzpsulta sericea and Magicicacla sepLeudecim vere exnminecl by 116. There the sensilk are very n ~ ~ i r i e r o u ~ ; all on tlie nnder surface, most on the first flagellar segnient, but niany also on the succeeding ones. Less tliference 1)etween the two kinds tl iari mentioned by Hansen was seen, and tlie type wit11 projecting spike was found on other segments than the first. especially in ill. seyicea.


Uerlese (1909) discusses and figures the antenna1 sensills iii Tibicen plebeia (p. 620, fig. 745).

The tip of the rostrum in botli nymphs and adults is furnished with nunierous liairs wliich conceivably subserve a sensory function. A t lenst such an Iiypothesis i s more probable than the one held as recently as 1839 by Natlianiel Potter, who believed tliat moisture was absorbed through them or, rather, “ exhalations of vegetable barks.”

6. MUSCULAR SYSTEM.

A very detailed account of the musculature of Tibicerz plebeia is given by Berlese (1909, Cap. 8, figs. 452, 464, 466, 481, 496- 498) and compn.red with that of other types. The complexity of the trunk muscles in general is not dissiniilar to that attained in Lepidoptern.

The muscles of the mouth-parts have been referred to in the account of these organs, RS also those of the auditory and sountl- procjucing apparatus in corresponding places.

For the general trunk muscles we refer to Berlese, a s cited above.

The recta.1 sac is strorigly mt~scula.r, expelling the waste liquid lvitli colisiderable force a s it thin jet.

‘File tyrnb:rl iriuscles form the largest and strongest pair of muscles in the cicada body.

c. RESPIRATORY SYSTEM.

01. Spiracles. There has been much confusion concerning the number,

position, arid terminology of the spiracles, especially in CicaclidE, but also in Hemiptera. i r i general.

Yufour (1883, p. 258) recognized in Cicada o v ~ t i six pairs situated v e n t d l y at tire intel.nd side of a, deep longitudinal fold. fze described these “ ostioles ” as lacking peritrernes and as placed or1 sKla11, ronirdetl, whitish, somewhat salient spots.

p;&nrd * a t t r i h t e s t o Hemiptern arid Orthoptera two pairs of thoracic spiracles present on the t w o anterior segments. 80 far :ts we know, no oiie receiitly has suggested t1ia.t the first, spiyacles belong to the protllol-ax.

Lalidois (1867, 1874) considered spiracle ( 3 ) to be a “ Schrill- st,ignia,,” the efficient instruiment in the song of the cicada The t,rne souncl-orgnris he considered functionless.

Schiodte, in 1870, iiidicat,ed ten pairs of spiracles in all Herniptern-three thoracic and seven abdominal, the former lying or1 the hinda: etlges of their corresponding segments.

Ha.ndlirsch, in 1899, from a. study of the relative size of the spiracles and of the branching of the trachea decided that,

* 1‘ On the Distribution and Primitive Number of Spiracles in Insects,” Amer. Nat. viii. pp. 531-63L (1874).

YOXPYOLOOY OF THE CICADIDAL 427

the third spiracle in Hemipterawns really the first abdominal. H e found it in some cases on the hind border of the metathorax, in others on the intersegmental membrane, and io others on the first abdominal segment. The first abdominal segment he found was greatly reduced, and had been overlooked by t n xonomists, who had practically universally callcd the second the first.

Heymons, i n 1899, observed that in the nymphs of mnny species of Heteroptera the first spiracle is on the meso-, the second on the metathorax, and the third on the first n btlominal segment, but in the colirse of development there is R movement

Text-figure 62.

Carinetaformosa. Female : latero-dorsal view ; the stomach sliglltly displaced.

.e., entrance of Malpigliiau tubules in to wall of stomach atjunction with mesenteric (Other lettering as SRC j tr., position of tracheal knot viewed from within.

in text-fig. 61.)

forward, so that the first lies between the pro- and inesothora.x, and the third on the 1netathora.x. The first segment in the abdomen to show a stigma distinctly on its surface is the true second.

Hansen (1902, pp. 214-216, transl.) p v e the first cleta.iled description of cicada spiracles, thoiigh Handlirsch had studied the nymphal e m v i e of one form. Hansen’s results may be summarized as follows :-

1. The first spiracle lies between pro- and met;othorax in the articular membmne.

2. Occupies a similar position between meso- and nietathorax. It is almost perpendicular.

428 DR. J. G . MYERS OW TWC

3. “ The first piir of abdominal spiracles lies on the ventral side of the body close to the lateral margins iii a de1)ression at the base of tlie :ibdorrien, surroumded by 3olitl chitin \a p r t of the nietasterri~ini), which, particu1:dy in the rnale, is very tliick arid of considerable breaclth. They are trarisvelse like ti10 thoiacic spir‘xles, b u t somewhat diorter tl iaii these. . .”

4. The second abdominal spiracle is on tlie underside of the body, facing forwnrdb mtl towards the insect’s mitldle plane.

5-10. .. E:rtch of the third t o eighth wbtloniinal spiracles lies i n the stercite itself, a little helrind its frout margin. . .”

Spiracles 4-10 inclusive are considerably smxller thail the others, and of different structure ; they are entirely open, with an oval o r almost circular orifice, tlie peritrenie being a solid ling, wliicli is also furnished with a great number of hairs directed towmls the centre of the spiracle (Hnnsen, 1. c . p. 216).

The condition in Afelctnapsulta nzuta is :I,\ folloivs :- We number the spiracies consecutively in one series, owing to

the dispute as to whether number 3 is thoracic or abdomirial. 1 . As described by Nansen. The trunk enteririg from it is

very laige, but the spiracle itself difficult to see. It is very slit- like.

This is more roundetl t h i n ( a ) and lies i i i tlie intersegmental membrane between mesotliorax and nietathoiax, just below base of tegiiien.

3 . (Text-figs 16, sp. 3, 17, 18. 22.) This is just beneath outside m g l e of the operculuni. 4. (Text-figs. 19, 20, 22, sp. 4.) This lies in close association

v i th the auditory capsnle, and is seen only in facial view in the unt i eated specinien. Hansen’s deecription is good, except tli;tt tlie spiincle is really on segment 1. (text-figs. 19-21 ; we latei).

5-9. As tlescrilrierl by Hanseu. These are shown in text-fig. 11. 10. This is difficult to find.

2 . (Text-@. 9, 22, sp. 2 . )

It lies in the intersagmental nieni- bixrie in the angle between VIIItfi tergite slid VIIItli sternite (text-figs. 13, 35).

I n Z‘hopJw saccacta the 5th spiracles arc covered with a white pruinose nisteriiil, u hicli, with their i,xised rims, renders theiii highly conspicuous.

We are now concerned with the question as to whether t he 3rd spiracle is thoracic or abdominal, as we have seen it lias mucli iiioi e in coninion with the preceding (thoracic) ones tlian with the succeeding (abclominal).

Yet if we accept tlie evidence of Hanclliiscli and of Heymons, confirmed and accepted by Dogs in iVepa (1 908), by Hegeniarin in C0ri.m (1910), by Hoppe in Xotonecta (1911), and by Wefel- sclieid (1912) in Plea, i t would appear tliab i t is abdominal in or~igin. Moreopeel., the latter origin is almost a logical necessity unless we are prepared t o admit a prothoracic spiracle. I-Iansen, who was the first to point out tha t spiracle 3 in Cicadidrc differed

. .

MOBPHOLOGY O F ‘PHIL CICADIDB. 439

from the thoracic type, and who also expressly stated that i t is surrounded by solid chitin of the inetasternum, yet continued t o call it first ccbdonainccl.

Crampton * subscribes to the theory of a forward migration of spiracles as described by Heymons. Snodgmss (1921, p. 403) refers to the spiracles lying just before the tymbals in a male cicada as those of the first abdominal segment. These are our sp. 3 (text-fig. 17). Kershnw and Muir (1922, pp. 202, 206) refer to the last spiracle a s the eighth abdominal.

Vogel(1923) accepts Heymons’s results and considers spiracle 3 as now definitely placed on the metathorax. H e was the first to

, I lext-figure 63.

Carineta fwmosa . h’cinale : ventro-lateral v ~ e w to show tracheal knot on surface of mesenteric sac. (Lettering as in text-figs. 61 and 62.)

indicate that spiracle 4, in front of the auditory capsule, is topographically now attached t o abdominal segment I., as shown in our text-figs. 19, 20, and 21, but by no means obvious unless a KOH preparation is made.

Finally, Mammen (1912) agrees tha t spiracle 3 is to be considered first abdominal.

To avoid confusion i t is best to number the spiracles consecutively in one series. Then and then only shall we know whether 6 ‘ metathoracic spiracle ” is meant to imply 2 or 3.

The most detailed description of the spiracles themselves has been supplied by Mammen (1912). H e studied the nymphal exuviz of ‘( Cicada gigantea” (= 12 Pomponicc g . Dist.) and the adult of a Plutypleura sp. from giautschou (probably P. kaempferi (Fabr.)).

* Ann. Ent. SOC. Amer. xi. p. 356 (1918).

PROC. ZOOL. S0~.-1928, NO. XXIX. 20

430 DR. J . G . MYERS ON TEE

I n the former he found the thoracic spiracles pleural, and tlie abdominal he considered to lie on the border of sternite and parasternite, in Complicated folds. I n essentials the closing apptratns is similar to tha t in adult Platyplewa.

In the latter the first spiracle showed very interesting specializa- tions. The niesothorax is anteriorly produced far forusrcl into the prothorax, so tha t the projectir~g hind margin of the latter covers a more or less enclosed spwe (Luftraum) in which lies the spiracle in question. There is an intricate closing airangenient with a special muscle, and, in addition, a complicated system of hairs and bristles t o prevent entrance of foreign bodies. This spiracle belongs to the type known as ‘( Visierstigmen,” i. e., the spiracle has come to lie in an insinking of the intersegmental membrane. and this depression has taken up an oblique position so that the stigma does not lie directly beneath the opening of the pit.

Text-figure 64.

Carineta,forinosa. Tracheal knot of surface of mesenteric sac immediately beneath left third spiracle. External view.

The second stigma lies between meso- and inetathorax and belongs to Mamnien’s ‘ L Deckstigma” type, in which the fore- border of tlie spiracle forms a kind of lid which fits over the opening right to the hind edge, to which i t may be tightly appresed by the contraction of a special closing muscle. Since this spiracle lies perpendicularly beneath the gap between two segments, the risk of entrance by foreign matter is great, but is obviated by the presence of numerous hairs and a chitinous plate which projects over the stigmatic openiiig fiom the fore edge of the met at 1.1 orax.

The abdominal stigmata in this Plcctypleum lie laterally on the fore-border of each sternite, so that each is slightly overlaid by the posterior edge of the preceding segment. The first abdominal spiracle is situated under the hind edge of the metathorax in r2 complicated fold. In the abdoniinal segments, in general, tlie integument sinks in to form a Eollom, at the bottom of which lies the stigma1 opening. The hind wall of the liollow

MORPHOLOGY O F THE CICADIDrE. 431

evaginates meclially as a. short, plump cone for the att,achment of the closing muscles. Further details should be studied in Mammen’s elaborate paper with the aid of his excellent figures.

8. Trachea The general tracheal system has received no comprehensive

treatment since the work of Dufour (1833), who distinguished in Cicada orni two kinds of trachea-tubular and utricular. The first, lie said, were distributed especially t,o the abdoniinal viscera and were very fine. Those ramifying among the digestive organs were enveloped in an adipose sheath ; those in association with the genital system brilliant and shining. The thoracic cavity was said to have two moderately large trunks distributing branches as far as the salivary glands and the rest of the head.

Text-figure 65.

Carinetaformosa. Male : dorsal view of enlargement of esophagus, posterior to true sucking-pump, showing five pairs of dilator muscles a i d their position in relation to supra-cesophageal gaiiglion (s.).

Dnfonr describes the iitricular trachea as, in general, small bull=, some globular, others of diverse shapes, more or less grouped, especially on the lining membrane of the abdomen and on the snrface of the thoracic muscle masses. Independent of these sinall bnllz there is a large conical titride on each side of the mesotholacic cavity.

Dufour believed that, in genei~al, very active insects show the greatest development of utricular trachez. H e was therefore surprised to find so few in Cicadidre, with their well-developed iriotor apparatus, but explains the deficiency by ascribing to these insects ‘‘ des habitudes shdentaires.”

A thorouglrgoing study of the whole tracheal system is much needetl, in ~ i e w of the controversy as to whether the large abdominal sac is tracheal or mesenteric. We ha \e referred t o

29*

432 DR. J. G . MYERS O N THE

this before and shall not discuss it l l o ~ , save to mention tha t we deal with it at length with the digestive system of which we think i t a part, and to state that, in the examples examined we were able to establish no other connection with the tracheal system than that afforded by a. stout, short trachea from the third spiracle, running a t once t o the immediately adjacent snrface of the sac and there, without penetrating, forming a tiacirieal knot (text-figs. 63, 64) which breaks up into several bmnclies raiiiifyirig over the wall of the sac in question. This is

Text-figure 66.

carineta fornzosa. Entirely schematic longitudiiial section of posterior part of pharynx and anterior portion of esophagus.

mss., dilators OF second swelling of food-canal; msp., dilators of pharyngeal sucking-pump ; fp . , frontal plate of tentorium ; CB., cesoph;bgns.

the stigma, nevertheless, with which Snodgrass (1921 b) and Vogel (1923, p. 207) believe the sac to obtain its only communication with the outside.

Vogel (1. c . ) claims that the usual communicating longitudinal and transverse trachea3 are absent in cicadas, at least in the third to eighth abdominal segments. Nevertheless, in Fidicina (text- fig. 26) we are able to find a wide transverse trunk running in the tergal arch between the fifth spiracles (third abdominal), and betweeii the inenibers of the same pzir a finer ventral trachea,

II1ORPHOLOGY O F THE CICAUIUB. 433

From the immediately preceding spiracle :I large trachea likewise arises, but branching soon, it fails to form a transverse trunk (text-figs. 25, 26).

The tracheze of the seventh pair of abdominal spiracles are said t o be devoted wholly to the service of the niycetornes, the elements of which are bound together into the seniblance of an organ by their smaller branchlets.

That all the spiracles, apparently without exception, are, however, linked up by a longitudinal trunk on each side is obvious from an exaniination of the nymphal extivia The connection between spiracles 1 and 2 is a particularly stout trachea.

To sun1 up, we know tha t there are transverse trachea: between the spiracles of certain pairs, and longitudinal ones connecting the spiracles of each side. There is also a conical air-bladder on each side of the mesothoracic cavity. Further elucidation of the tracheal system must await the acquisition of fresh material for dissection.

d. ALIMENTARY SYSTEitI.

a. Bistorical Review. The widespread classical belief tha t cicadas lived only on dew

nas based probablyon the absence of any striking signs of injury to the plants frequented by these insects, and partly n o doubt on the lack of anything wliicli the unskilled obser ver could recognke as an effective mouth.

The first name associated with an actual dissection of the cicada digestive system is one which “ every schoolboy knows.” Meckel, in 1808, gave a surprisingly detailed description and figcire of conditions in Fi“ihicen plebeaa. H e stated tha t the whole canal was a t least ten times the length of the body. H e distinguished esophagus, stoinach, “ einen aus diesem entspringenden uric1 in ihn znruckkehienden langen Kanal,” a long thin and a short tliiclc intestine. The mesenteric sac is shown i n its correct relationship, biit the true intestine runs out of the esophagus- probably he ruptured the thinner part of the stomach. The salivary glands were explainer1 thus :-“ Es sind offenbar Organe, die rine Fenchtigkeit absondern, welche cler Cigale das Anbshren des I Iol~es erleichtert.” (p. 3.)

The next worker was Ranidohr (1809, lS l l ) , who largely followed Meckel so far a s cicada anatomy was concerned, but appears to have discovered the suspensoiy “ ligament of the anterior projection of the mesenteric sac. This, however, seemed t o liini SO noma ma lo us that lie regarded i t “conime un tissu accidental e t contre nature.”

Marcd de Seiies (1813) atlded little save the statement that the NIaIplghian titbiiles entered an enlarged part of the cesopliagns.

W i t h his great countryman Dufour, however, i t was far otherwise. This observer lair1 the folindation for a knowledge of the internal anatomy not only in Heiniptera, but also in several other

(Dnfour, 1825, p. 161.)


insect orders. I n 1825 he described the main parts of t he digestive system with great clarity, and clainied tha t “ les Cicadnires sont jusqu’& ce jour les seuls insectes ou ce ligament subpensenr [of the niesenteric sac] existe.” (p. 161.) H e ex- plained this latter ss due largely to the habitual vertical position of these insects. I n 1833 he published an amended account of the digestive system in Cicucln orni. Perhaps the one point on which he was inistaken lay in supposing tha t the (‘ intestiniform tube” in ascending opened into the cavity of the stoniach rather than coursed merely in its walls.

The fact of the latter condition was established by Doyere in 1839 in a paper criticising Dufour’s work and claiming, further, tha t the latter was incorrect in describing four Malpighian tubules since there were only two.

To this Dufour (1839) replied, accepting very gracefully the correction concerning the filter-chamber, but, re-assertirg h i s belief that there are four Malpighian tubules, i n which cf cowee he is abundantly confirmed.

Text-figure 67.

Melampsaltp leptomera. Salivayy pump. a., lateral view of wliole organ from left; b., ventral view of

entrance of sa1ivar.y duct.

Lubbock (1859) described the “ internal gland ” of Coccids. Later workers on cicaclfin splanchnology have been Schindler

(1878), Nassonow (1899), Quaintance (19021, Gxdd (1902, 1910), Ha.rgitt (1903, 1923), Lirent (1911 a, 1911 6, 1912), Berlese (1900), Kershaw (1913,1914.), Hickernell (1920, 1923)* Snodgrase (1921 6). Gxdd’s paper (1910) is of great value i n tha t it gives conipa.rative data on eight species in the genera ITibicem7 &ado, Ck&itm, :i nd Me~cmpscdtc6.

Burnett (1851) clfi.imed tha t in Jfagicicccdn septendecim thcre was n o trace of the digestive syst,em in the mde. La,ter American entomologists, even as recent as J. B. Smith, believed that the gut, was more or less atrophied in this species.

Finally, t,llere are those who, like Cnrus and Graber, interested priniarily in the sound-producing apparatus, took the mesenteric sac for an air-bladder of the tracheal system. Appa.rently the only one who has hdcl t o this belief R.fter dissecting the d imen- h r y tract is Snodgrass (1921 6). All the other workers cited above have given an interpretation, wit,h which, in essentials, t h e account set out in the following p g e s will be found to agree.

MORPHOLOGY OF THE CICADIDB. 435

p. Gewerul View. It will conduce to tlie clarity of the succeeding account if me

prefix it with a sketch of the salient points of the whole digestive tract (text-fig. 60).

FunctionalIy the first pnrt of the alimentary canal consists in cicadas, as in all other Hemiptera, of an extremely fine passage between the closely-apposed mouth-set%, which are themselves enclosed in the trough-like rostrum. Soon after entering the head the food passage widens into a capacious and powerful sucking-pump, a dilated portion of the pharynx, which is succeeded by a smaller but muscular swelling jus t below the entrance to the thorax. A t the posterior extremity of the thorax the esophagus enters t h e pecnliar complex known first by Lubbock R S the internal gland (in Coccirls), but now more generally termed

Text-figure 68.

Mggicicada septendecim. Stj lets iiiserted in branch (from Quaintaace, 1902).

the filter-chamber. The essence of this arrangement consists in the zig-zagging of the nxending part of tlie mid-intestine in close association with the attached portions of the Malpighian tubules in the actual walls of the anterior part of the stomach. By this construction it is believed that the watery constituents of the plant sap (Licent), or these and the surplus sugars (Berlese), I)"\" directly by dialysis through the lining of the stomach and t l 1 P malls of the intestine, and thus are carried direct by the rectum to the exterior j while the more nutritious elements are \elected to pass by the more circuitous digestive route. The f o r e p ' t of the intestine thus forms o long and very intricately coiled loop which appears finally to end in the stomach, as indeed l h f o u r oiigiiinlly believed it to do. The position, already complicated by the serpentine twistings of the intestines and

436 UR. J. G . MYERS ON THE

Ma!pighian tubules, is further obscured in cicada by the extrcl- ordinary development of a huge, thin- walled, mesenteric sac, occupying most of the abdominal cavity in the male and considered by Graber, Snodgrass, n.nd many others as an air-sac of the tracheal system. It is, however, a part of the stoimch in direct cominuuication with the cavity of the interior part of the latter (not merely of the filter-chamber), a,nd gives rise at its own posterior extremit,y to the ascending mid-intestine, which, after many convolutions, enters the main stomach-wall near the junction of this main stomach with the mesenteric sac. After a. tortuous course within the wa,lls this tube receives the Malpighian tubules which have acconipanied i t within the investmerit of the stomach, then joins the posterior intestine at the anterior end of the stomach, which it leaves n e w tlie entrance of the esopha,gus, a.nd proceeds nfter much winding to the musculnr rectn.1 sac which opens to the exterior on segment X.

r t 1 ext,-figure 69. _ - - _

_ _ - =Q - - - - \ \

:::,q) a"); ' \

- - _ _ - ._ - _ _ - - _ .--_ x . . _ _ - r

Jfa.qi&ada septeiadecinz. Sensillre of first nutairrid flagellar segment

The salivary glr7.11ds nppear R S bunches of lobules filling the greater part of the head-cavity. Their deferent cannls unite to form a single duct carrying the salivary secretion to the salivary pump or syringe, wliicli forces i t down tlie sinaIIer of tbe two maxillary channels into the pierced plant-tissue. The juice from the latter is sucked rip the 1;Lrger 01' food-c:mal formed by the close apposition of tlie maxillnry settr.

y. Horpholoyg. i. Xozcth and i ts Appendages.

The food-passage begins with the mouth, but i t is largely all acaclemic question where tlie moiith lies. Rugnion and Popoff (191 1) consider it to be at the tip of the rostium: xnd functionally the entrance of the tube between the apposed maxillary set= must be the mouth, even when the stylets are sunk in tissue fat- beyond the t ip of the labium (test-fig. 68). Embryologically the opening of the storiiotlmni corresporids, liowevei., to the egress pore of the stylets from the head-cspsule before they enter the labial trough a,t all. AS shown by Snodgrass, this is the functional

MORPHOLOGY O F THE CICAUIDB. 437

relic of a very wide orifice whiclr extends between the apposed edges of the epipliarynx and hypopharynx. Into this niouth- pore opens a short,, narrow tnbe, found by Meek to be strongly chitinized, which is the beginning of the pharynx ; and to this same spot the efferent duct of the salivary pump, opening actually at tlie tip of the hypopharyiix, delivers the salivary juices.

ii. Pharynx. Foilowing the narrow, chitinized tube is an extremely wide

chamber lying in the boat-shaped chitinous trough formed largely

Text-figure 70.

MeZampsaZta se i - icea . Male : dorsal view of chief gmglia of central nervous system; drawn in one plaue.

oc., coininon s tmi o f ocellar nerves ; op., optic nerve; 6., supra-esophageal ganglion; c. , tcsopl~ageal connective; sy., sub-esophageal gmgl io i i ; tg., gaiiglionic masses of thorax.

by the frontal plate of the tentoriuin. This is the suckiiig-pump. A t rest tlie dorsal wall, wliicii is strongly invaginnted, touches the floor. which is fused both in old nymphs and in adults to the chitinons sribstaiice of the frontal plate, though Muir says it may be separated in a nymph just after ecdysis, before the chitin has ha2 dened. Thus tlie whole of this plmiyngenl chamber, despite the commonly-accepted opinion, is niembraiious except for a

438 DR. J. G. MYERS ON THE

chitinous median longitudinal portion of the deeply invaginated dorsal wall. Here are inserted the very numerous and feathery muscles which are attached t o the inner surface of the swollen frons, whose striations correspond with the attachments of these muscles (text-fig, 66). I n the nymph of Neelffimpsalta &g&ta, and probably in others, the front is much more swollen and smoother than in the adult, hut the striations are marked with liries of bristles which are used as a cleming apparatus for t h e

Text-figure 71.

- . . . . . . . . . . -. .

Carineta formas.%. Male: dorsal view of dorsal vessel.

I.-IX., abdominal segments; ao., aorta.

fossorial fore-limbs. Snodgrass considers this sucking-pump a part of the mouth-cavity and not of the trne pharynx (1927). H e is led to this riew chiefly by his belief that a true pharynx is always a muscle-covered organ, whereas the dilation under discussion is membranous and chitinous, i ts only muscles being the dilators of the roof. He finds tha t t he dilators of the mouth- cavity are mostly attached to the clypeus in other insects. This mould make the striated facial place, called by us the from, really


tho clypeus. Meek describes the pharynx or sucking-pump as formed by two troughs, one lying within the other-a very ap t illustration.

The sucking-pump leads backward into a narrow tube, which, just above the tentorium, dilates once more to form a strongly muscular sac, shown by Snodgrass (1921 b, fig. 6), but apparently

Text-figure 72.

Curineta fomzosa. Male reproductive organs, semi-dorsal vien-. t., right testis; wd., riglit w s deferelis; ws., left vesicnla seminalis; ej., ejaculatory

duct ; ced., zdeagus; ac., right accessory gland.

missed by Meek. I t was then considered by Snodgrass as a second bulb, but he now (1927) believes it to be the true pharynx. It is provided with numerous dilators of which the distribution is somewhat obscure (text-figs. 65, 66). Thus Snodgrass in ilfugicicadn septendecina found the first dorsal dilator muscie to go to the neighbourlioorl of the mer1ia.n ocellus, the second to the dorsal arms of the tentorium, the third t o the lateral parts of the

440 DR. J. a. MYERS ON T'UE

vertex, and the fourth to the occipital margin. In addition he saw two pairs of htera l iniiscles proceeding to the posterior arm of the tentorium. The brain mas found to lie on the surface of the organ before the first dilators. This was taken as evidence that severd anterior dilator rnuscles of biting-insects are here suppressed, since these ordinarily arise from between the bands of cii-cular muscles, the absence of wEiich in the sucking-pump ma,kes Snodgrass deny its identity with the pharynx, extending soiiie distance in front of the ganglion. But in the Paraguayan Cicri7zetrc formosa (text-fig. 65) studied by us, while the diatribu- tion of the dilator muscles on this second enlargement agreed in the main with Xnodgrass's notes on septeizdecinz, yet the brain

Text-figure 7 3 .

Curineta forntosa. F m a i e reproductire orpins, ventral t-iew. ow,, right ovary; o., left oviduct ; ac., left accessory gltnid; co,, commoii oviduct;

sp. , spermattiece ; acs., basal portion of left sperinatliecnl gland.

was ensconced on the surface of the swelling distinctly behind the roots of a group of at least two pairs of dorsal dilators. The posterior dorsal dilator niascles are in close relation with the anterior extremity of the aorta.

iii. aSsop7~uy.u.~. Behind the second enlargement, and just before entering the

bhorax, the food-canal, now the cesopliagus, makes a sudtlen downward bend 50 that the subct?sopliageal ganglion is directly anterior to it. Throngh the thorax the cesophagus, tightly enclosed between the great, lateral muscle masses, shon s little differentiation, although hodgras s (1921 b ) describes and tignres

DIOHPIlOLOGY O F THE CICADID& 441

in Xugicicada s e p t e d e c i n z a transversely-corrLigatec1 distensible crop or proventricnlus. Such a structure. if present a t all, is very much less developed in Carineta fornzosu.

A t the entrance into the stomach ih the very effective ccsopha- Seal valve. Following Licent (1913) and Kershaw, we regnrd the remainder of the alimentaiy tract to the pyloric valve as mcsenteric in origin. IIickemell apparently does not accept these as landmai.ks, since (1920, p. 226) he states tha t in cicadas “ i t is difficult to recognize the boundaries of t8he fore, mid, and hind guts.” I n stating tha t the whole of the canal between the miophngeal valves and the pyloric valves is mesenteric in origin, 1 do not wish t o claim that this portion is derived entirely from endoderm, but rather tha t it cloes not form part of the embryonic invaginations, stomoclzeal arid proctodzeal. Kershaw (1913,

Text-figure 74.

Carinetafommosa. Female : part of reproductive system, ventral view. (Lettering as in text-fig. 73.)

p. 176) considers that in i%pha?Ztffi acutu at least a part of this t iact niay be ectodermal in origin. The whole of the region thus delimited is lined with bare epithelium rather than with chitin.

iv. Stomach and E”ilter-chamber. A t the junction of thorax and abdomen, or a little before, tile

cesopllngus enters the stomach, the entrance being guarded by a r:tlve. I n Carineta part of the stomaah may lie even in the tlioyacic cavity before the mesophragma.

Tlie stomach (text-figs. 60-63) appears as a bilobed sac, called by Hickernell the anterior crop and by Kershaw the pouch or filter-chamber. The esophagus enters the anterior lobe slightly beneath and behind its anterior end (text-fig. 62). The first lobe is opaque, apparently niusctilar, and with an irregular surface,

442 DR. J. G . MYERS O N THE

while the second is rather thin-walled and spherical. By the position of the esophageal valves this stomach must be considered part of the mesenteron, as Licent, Kershaw, and Snodgrass seem to agree. I n some of the other Auchenorrhyncha, and especially the Cicadellidz (Jassoidea), the anterior chamber forms a much more distinct diverticulum of the stomach, and is there called by Licent the poche. It would seem to be homologous with the huge anterior diverticulum which Kershaw found t o extend into the cephalic horn of lantern-flies and other Pulgoroids, bu t these insects differ from most of the other families of the Auchenor- rhyncha in lacking n filter-chamber altogether.

The condition of the stomach in the Paraguayan Cchrineta fornaosu is not quite like that of any hitherto described species, but resembles nearest the figure (pl. 4. fig. 5) given by Kershaw (1914) of an undetermined Trinidad form. It may be best comprehended by reference to text-figs. 60-63. Although it

Text-figure 75.

Carilzeta formosa. As text-fig. 74, but dorsal view. up., apical pouch of spermatheca j ms., muvculal ploamal part of spermatheca.

curves collar-like in a very intimate manner partially around the anterior portion of the mesenteric sac, it does not communicate with the cavity of the latter until near its own extremity closely adjacent to the spot where it receives the mid-intestine on its way from the posterior end of the mesenteric sac. The course of the mid- or ascending intestine in the thin wall of the second lobe of the stomach is relatively simple. and nray be followed with ease from the outside ventral aspect. The four Malpighian tubes enter near the same spot, on the wall of the passage between the stomach and the mesenteric sac, but they are dorsal in position and run almost directly into the thick mall of tlle first part of the stomach, where they are immediately lost to siglit. The course of the intestine and Malpighian tubules within the wall of the filter-chamber or first stomach-lobe is difficult to follow. Their coils are extremely thin-walled. Here it is tha t the chief arrangements of the filter-chamber function. The loops and zigzags of the intestine within the chamber are,

MORPHOLOGY OF THE CICADIDLE. 443

however, much less coinplicated and numerous in Cicadidte than in CercopidE, where the peak of evolution in this matter is reached. Both Licent and Kershaw confirm this independently. In Curinetu formosa the intestine keeps rather closely to the anterior and ventral wall of the stomach, passing, however, dorsad of, and anterior to, the entrance of the esophagus, and then curving round, receiving the Malpighian tubules and passing out of the stomach-wall as the hind or descending intestine. The Malpighian tubules follow a more dorsal course.

They

li montrent une structure de l’epith6lium des lacets intestinaux toute differente B la fois de celle des Cercopidae e t de celle des autres insectes du groupe. . . . Les lacets [folds of the mid- intestine within the filter-chamber] b cause de leur dkveloppe- ment, peuvent bien filter l’enii, mais leur Bpithdium a l’air beaucoup moins specialis6 dans cette fonction que celui de toutes les autres cicadines B poche.“

W e have considered throughout, as dissection seems to show and as Licent asserts, that the intestine and the Malpighian tubules in the filter-chamber are actually in the wall of the stomach between the epithelium of its lumen and the external muscular investment. Bu t Kershaw (19 14, p. 66) explains the condition differently, as follows :-

“The zigzags of the various parts of the gut do not pierce the walls of the pouch in order t,o enter or leave it, but are merely enclosed between its exterior wall, the peritoneal membrane, muscular and connective tissues sealing up their entrances and exits and the narrow gap or slit-like opening between the exterior walls of the pouch.”

Hickernell (1920) expressed somewhat the same view, but the distinction is largely a merely verbal one, since the peritoneal membrane of the stomach (pouch) is, after all, a p a r t of its investment. The striking feature anatomically is tha t the membrane separating the very thin-walled intestinal and Malpighian filter coils from the lumen of the stomach is extremely thin.

Muir (1923, p. 213) credits all the Auchenorrhyncha except the Cicadellidze and the Fnlgoroidea, and all the Sternorrhyncha u~ithout, exception, with a filter-chamber, and draws phylogenetic conclusions therefrom, on the assumption that such a structure probably did not arise nioie than once. But J icent h a s shown that, though the filter-cha mhcr niay be physiologically similar throughout these groups, i t differs greatly morphologically. The dirergence between Auclienorrhynclioiis and Sternorrhyrichous conditions is especially great, as Licent remarks (1912, p. 29) :-

‘‘ I1 est absoluinent impossible, nu point de vile anatomique cl’assimiler a aucun clegre, B ces formations des Coccidae, la poche rles homoptbres superieurs dans laquelle l’cesophage ni le rectum ne sont absolument pas engagBs.”

The condition in Cicadidze is somewhat peculiar.

(Licent, 1912, p. 88.)


Similarly, Hickernell (1923, p. 214) says :- ‘( Berlese (1909) describes the digestive organs of certain

scale insects. I11 these insects the rectum is large and extends anteriorly a5 fa r as the esophagus. This results in :I knitting together of rectum and cesophagus, and also cames the intestine t o describe a complete circuit of the abdominal cavity before it finally joins the rectum. This condition, while resembling it superficially, is entirely diferent from the arrangement found in the adult cicada, since in the latt8er the relatively enormous enlargement affects the midgut, while the rectum is small.” Hickernell (1923) found that the filter-chamber is typically

developed, even in the newly-hatched nymphs, a result to be expected from the similarity in feeding-habits throughout the life-history ; so this condition evidently arises in the embryo.

v. The Mesenteric Suc. This is one of the most disputed organs of cicadan anatomy.

By far the greater part of the abdominal cavity, often in both sexes, but especially in the male, is taken up by a huge thin- walled sac (text-fig. 60, n ~ . ) of which the greatly wrinkled anterior portion is wedged in the V between the two large tymbal muscles, and is produced into a horn extending into the thorax and suspencled from the esophagus by a tendinous band. This is the sac which Graber (1876, pl. i. fig. 5, Be.) and Snod- grass (1921) claim as part of the tracheal system, while Vogel (1923) believes it accessory t o the auditory organ; but in the sonth American Carineta jormosa I find that not only has it no connection with the tracheal system, but tha t it also opens wiclely

definitely into the anterior part of the posterior portion of the stomach, thus confirming the views of Dufour, DoyBre, Nassonow, Gadd, Licent, Kershaw, Hargitt, and Hickernell. Licent calls it le seynae7at c o n i p e of the dilation ventriculuire ; Kershaw refers to i t as a sac of the midgut j while Hickernell names it posterior crop. Soorlgrass (1921, p. 403) considered tha t this sac, as a part of the tracheal systeni, received its air-supply directly tbroug2i the first abdominnl spiracles (sp. 3), which lie just before t,he tympana, but Hickernell (1923, p. 220) writes :--

6 ‘ It is easy to be deceived as to the continuity of the lumen of the posterior crop with the exterior through these first abclominnl spiracles. I n gross dissections there is only the most delicate epithelial membrane limiting this abdominal sac in the region of these spiracles. . . . If a specimen is allowed to become dry, the portion of the wall which is in front of the spiracular opening may easily rupture, :tnd then there is an external opening in fact. Sections show that the spiracle opens into a very small chamber the walls of which break up almost immediately into a number of tracheal tubes [text- figs. 67, 681 which distribute themselves over the external surface of the posterior crop. I ani therefore still inclined to

MORPIIOLOGP O F ’l’lIE CICADIDE:. 445

question any interpretation which gives this organ a respiratory fnnction. It certainly hecoiiies modified ill later life, but it is n.t all times a, part of the digestive system. This condition, which is easily observed in sections, inalres uniiecesssry the postillation of any secondarily derived function on the part of

The rnethorl of gross dissection, then, is inadequate 11.

n the conditions found.”

Hickernell further notes tha t the interior of a tracheal sac should hn.ve a. chitinous lining, while sections demonstrate con- clnsively tha t the present orgnri is lined with epithelium, although in the rriiildle portion the walls become so extremely thin that the cells may be cuboid or even squamous instea.cl of columnar.

O w gross dissections (text-figs. 63, 64) and shose of Lucas (1887) confirm Hickernell’s results concerning the relation between the third spiracle and the adjacent wall of tlie ineseiiteric sac. These relations are so close tha.t we suppose i t within the boiiucls of possibility for the sac thus to gain an opening with the exterior similar t,o t ha t described by Suodgrass. Rut the fact would nevertheless rernairi that the connections with the rest of the digestive system a,re primary ancl funtlninental, and the communication of the mesenteron with the exterior through tlie body-wdl direct wonlcl constitute a condition so anoma.lous that the proof required to estitblish it would he almost as rigorous as that tlerna,ntletl by Huxley for the presence of a unicorn trotting down the Strand.

Wit,h regard to the extent of the sac, Hickernell found in extreme cases tha.t it went back as far as the VI th segment. In Cffirineta, in the male at least, itas development is greictei- still. J7Tickeriiell ascertained that the size of the sac increases not only with the life of the adult insect, especiallg with decrease in size of the fat-body, but also throughout ontogeng. I n the nyniph (1 923) i t is much smaller and considerably folded, with a tortuous liinen. I n the adul t male, as noted first by Hickernell, its walls may. closely a.pproach the actual integument on all sides, lenving extremely little space in the main part of the abdcrnen for the orgams of circulation ancl reproduction, and for the profuse coils of t>he intestines a.ncl Malpighim tubules, all of which, as Snorlgrnss puts it, are in places janiined in a space no thicker than R piece of paper. Hickernell is inclined to hoinologise this pea.$ sacculax diverticulum with the prolongation described by Kers1~a.w iii Fulgoroids and st~ated in his earlier work to arise from the cesophagus. But, a,lthough this latter has also been shown now to he of mesenteric origin, s e t both Kershnw (1914) a,ncl Licelit (1912) agree in homologismg it with t,he poche or filter-chnmher of the columate Suchenorrhyncha. There is certainly no doubt that the two organs are morphologically disfiimilar in origin, though both mesenteric, bnt wbether they may not serve the same function is another question. Licent shows in a very instructive manner that throughout the

3Q PROC. ZOOL. S0~.-1928, NO. XXX.


Auchenorrhyncha" the meaenteric sac (flegment coniqzce) increases in size with reduction of the filter-chamber. Thus the former is large in Cicadidz, where the filter-chamber is somewhat reduced, while in Typhlocybids, where the latter is altogether absent, the sac becomes simply enormous.

vi. The fxicl-intestine. The part of the alimentary tract now to be considered is csllecl

by Licent the mediintestin, of which the free portion forms the boucle mediantestinale or the anse rnecliintestinale. Snodgrass names it '' the tubular continuation of the stomach," Kershaw simply " midgut," and Hickernell " ascending intestine." Ainong the coils of intestines and Malpighian tubules coating the exterior of the mesenteric sac the portions pertaining to the mid- intestine may be distinguished macroscopically from those of the Malpighian vessels by their larger calibre and smoother surface, and froin those of the hind-intestine by their colour, as remarked by Dufour in 1833. Similarly, Nassonow found it crammed with yellowish granules. A t the posterior extremity of the mesenteric sac is a knot of yellow tubes consisting of the first portions of the mid-intestine. This may be unravelled and the continuity of the mesenteric sac and the mid-intestine may be demonstrated, but the lumen of the latter is so minute tha t the actual communication can be confirmed only by sectioning, as has been done by Hickernell, Licent, and Gndd, while Kershaw shows the same passage in his figures (1914, pl. 4. fig. 5). The numerous and comp1ic:tted yellow folds of the mid-intestine disentangle themselves eventually froin the intermingled fat and Malpighian tubes, and the distal portion enters the filter-chamber, as described in the account of that organ.

Licent found that the mid-intestinal loop in the Cercopicla showed a constriction new the end of its proximal third. Gacld (1902) believed that this constituted an actual stoppage, and regarded, therefore, the whole loop as two csca joined a t their distal extremities. B u t Licent demonstrated histologically that while the two portions were different in structure and apparently also in function, yet the lumen was never entirely blocked at the constriction as stated to be the case by Grtcld. Nassonow had earlier found the lumen continuous in the Cicadida, and Licent discovered far less histological differentation between the two parts in this family. Such may be regarded as a more primitive condition than tha t prevailing in the Cercopida and most other coluinate huchenorrhyncha.

The mid-intestine is joined by the Malpighian tubules just before the pyloric valve, which in most of the Auchenorrhyncha is marked by an externally visible swelling, but which in Cicadids seems not to have been noticed.

* Licent persists in calling the Auchenorrhgncha " Homopthes supdrieurs." I f " height " means anything a t all phylogenetically i t connotes specialization, and the Sternorrhyrichn are very much the most highly specialized of all Hornoptera, albeit it IS in many respects a specialization by reduction.


vii. €find-intestine and Rectum. The hind-intestine as it issues from the filter-chamber is grey,

and easily distinguishable, even in i ts most complicated coils, from the bright yellow mid-intestine. I n Curineta formosu its distal extremity enters the strongly muscular, pear-shaped, rectal SAC nearer the *‘stalk” of the latter than in Magicicudc6 septen- decwn, as figured by Snodgrass and by Hickernell (see our text- fig. 60). The rectum is confined to segments VII I . to X. (or XI.)’ and lies very close to the dorsal integument. As Licent remarks :--

“ La forte musculature de cette poche expiique surabondam- ment l’dnergie avec laquelle les homoptkres etudiks en ces pages projettent les goutelettes pleines qu’ils evacuent par l’anus en si grand abondance.;’

Nassonow describes the little twist made by the hind-intestine as it enters the rectal pouch. I n this twist are incorporated the distal exti emities of the Malpighian tubules.

viii. Salivary Glu7zd.s a d Pump. The first detailed description of the salivary glands in Cicadida

is apparently tha t of Dufour (1825), amended in 1833. His account is reinnrkably accurate.

&[any wiiters have been fascinated by the salivary pump of Heniiptera, and since this organ shows little variation in essentials, their descriptions ai e largely applicable to Cicadidze.

In 1910 Bugnion and Popoff studied in detail the salivary glands of iiuinerous representatives of the order, and concluded with a description of conditions in Cicudu o m i . This has been in p i r t confirmed by Snodgrass (1921) in ilIugicicada septendecim, and by ine in CcLrinetu formosu and in several New Zealand ,pecks of Il.leelampsulta.

The glands form whitish digitiform lobules clustered in oiinches and filling most of the head-cavity between the muscles, bnd extend also into the prothorax. There is an anterior pair ’orming the chief gland which supplies the principal canal, and L posterior pair-the accessory or aberrant gland-joined t o the irst by a short thick cord on each side. A third gland pair, bonsisting of a long filiform organ on each side with a small pheroid body in its course, joins the principal canal near its brigin. Thcre a l e thus, on each side, three canals meeting at he same place on the deep face of each principal gland.

The principal gland exhibits two kinds of digitations-larger nes to the number of sixteen or twenty and white in colour, n d smaller ones more or less transparent. Among the former, 1 C‘arineta we found several lobules (acini) similar in structure 3 the white ones, bu t deep black in coloui-. These were irregu- d y distributed among the others.

The principal canal unites, after a very short course, with that f the opposite side, and the common t runk runs to the salivary

. .

30*

445 DR. J. C . MYERS ON l H E

ptiiiip. I n Nelanzpsffiltcc leptomera (text-fig. 67) its entrance into the antero-ventral wall of tlie panip-ciianiber is flanked by t n o short, stout, curved transparent horns. I n Cicccdu o m i the debouchure is similar in position antl marked by a rounded swelling. In Xc~gicicffidcc, wliile Meek shows it simiiar here also, Snodgrass (1921 a, p. 6) states that the “colnnion clnct appears t o open :it the very t ip of the terminal point of the hypopharynx.” This is surely an error. Gacltl (1909, fig. 2) shows in Cicadatm at7u a coiiclition identical with that in Xelffimpsaltcc leptonzera.

The aberrant gland contains a score of lobules sirnilm t o those of the principal gland, but a little larger, more transpment, and easier to isolate. The cord joining i t tQ the principal gland has an opaqiie covering, formed largely of trachez (Bugnion &

The filiform organ is a very fine and delicate tube, in o ~ n i about 20 mrn. lorig. Beginning with a free, rounded, blind extremity it ninkes many turnings behind the liead and then joins the principal gland at its origin. Coniposed of the two distinct segments, ir, shows in its distal part a relatively wide tube with thick walls, furnished internally with cells badly delimited and difficult to distiiiguish (B. & P.). The proximal segment, niuch shorter, has a chitinous canal surrounded by n thin investment like that of the collecting canals in general. A t the junction of the two segments is a small rosette containing some atrophied glandular lobnles. Bugnion and Popoff consicler that this peculiar nberrffint gland, discovered by Ihfoui- in 1825, takes the phce of the great abdominal salivary gland of ‘‘ Fulgora.”

The salivary pump is a t iny but tough chitinous cylinder or elongate bell of transpxrent material lying beneath the tro1lgh-like frontal plate. The piston or plunger (text-fig. 67), s t ik ted deeply but sparingly in both I?felanzpsalta leptoinerffi and Cicada orni (B. cb P.), is darker in colour. The pump anteriorly * continues into a narrow heavily-chitinized tube opelling near the mouth-pore. Posteriorly the shaft of the p h q r e r expands into two branches, each serving for the insertion of it \vide and powerful protractor muscle.

Miiir antl Kerbhaw (1911, p. 79) have shown that the salivary p11111p is a difl’erentixted part of the common salivary duct, from which it arises in tlie embryo.

,IS regards the histological structure, Bugnion xncl Popoff found tll:Lt the glnntlnlar cligitations show an external cuticle supporting t r , ~ ~ l ~ ~ - ~ , arid in the interior a greyish cyt oplasni without distinct cell-liniits, and a branched nuclens. There is, to all appearances, a single nucleus or acinus in spite of its relatively large dimen- sions. Tho presence of these ramified nuclei gives to fresh pieces in saline :I peculiar aqpect ; the teiminal nuclear branches being a lit,tle tlilatetl, one sees in each lobule a great number of small ,wp]liiigs joined to one another by straight britlges. Finally,

Pelllaps ( 6 crp~lalad” woald be n clearer term.

Popoff).

?r the hypothetical positioii, \.ritll the head of the iiiscct poriect.

XORPHOLOGY OF THE CIlCADIDA5. 449

above the great ramified nucleus there are small multiple nuclei situated a t the surface of the acirius arid pertaining to the small flat cells just beneath the cnticle and concerned in its production.

Although minified nuclei of the kind described in Cicada are characteristic of insect salivary glands in general, yet the Gym- noceiate Heteroptera, studied by Bugnion and PopoE, show only simple oval or rounded nuclei in the salivary acini. This is a great divergence within the same ortler, and one would be inlerested to see how widely it extends.

Bugnion ancl Popof’s remarks on the pliylogenetk development of the Heinipterous salivary glands ai-e to be largely discounted by the fact that they regard the highly-specialized Aphidid= as lower forms, stnd seek to derive the coiitlition in Ciccldu, Ftdgoru, arid the Heteroptera from that in Aphides. The latter may have retained a primitive condition in this respect, but there must be no a priori assumption tha t such is the case.

Gadtl’s work on Yibicen plebeia, Cicada o m i , Cicadatru utm, G. hyulina, arid Xelccmpsaltn mo?ataiou seems to agree largely with that of Bugnion and Popoff.

ix. iVcdpigluiaiz il’tcbules. In the Cicdicle the relationships nncl even the number of the

Alnlp~gliian tubules are more obscured, firstly by their extreme lengtli, secondly by their participation in tlie riiesenteric complex kriowii RS the filter-chamber, ant1 thirdly by the inextricable iiiirigling of their distal extremities i n the final knot of the hind- iiitestiiie just as it enters bhe rectum. Froin this point the tiiluules zigzag over the surface of the rnesenteric sac until they enter the wall of the stomach near the entrance of the mid- intestine. The distal portion of the tnbules is much thinner than tlie proximal, as shown by Licent in Czcudoc orni (1912, fig. 28). I n the proxiiml portion. just after emergence froin the filter- cliaiiiher, tlie nnri.ow first part is succeeded by R very short, smooth, rather swollen section, apparently hon-rologous with a more noticeiLble swelling, greatly developed in Cercopidre and responsible for the secreticn of the viscid mate1 id, which gives tenacity to their foam or “ cuckoo-spit.” The reinninder of the tubule is varicose.

The i\Zalpigliian tubalw are four in number, bn t after ser- pentining in the filter-chamber, and just hefore joining the mid-intestine near i ts junction with the hind-intestine, two, nccoiding to Licent aiid to Pilassonow, reinain free, while the other two fuse into a ureter-a very unusual condition found by Cndtl and by Licent to occur also in the Cercopida Rut in Sq~tmdecim, Snotlgrais (1921 b) found that both pairs fuse, so t l i a t only two ureters join the intestine instead of one uieter and two tubules; while Keyshaw (1914, p!. 4. fig. 5) shows the same condition very clearly in an undetermined Trinidad cicada.

450 DR. J. C . MYERS ON THE

The histology of the Malpighian tubules is considered at great length by Licerit (1912). His masterly work should be consulted by all interested in the digestive system of Hornoptera. An interesting feature is mentioned by Hickernell (1920, p. 236) :-

“ A t the point where the tubules enter the ‘ internal gland ’ there i s . an abrupt change in the character of their walls. They become thin, the nuclei decrease in size and are less chromatic. They retain their niembranous character until they finally empty into the intestine near the anterior margin of the ‘internal gland,’ at the junction of the ascending acd descending intestine.”

A t the same time their lumen increases greatly in size-all of which is highly significant, in view of t he supposed function of the filter-chamber.

x. Othey AnrLexed Glands. The “excrementitious glands ” of Dufour (1833, footnote,

p. 225) are almost certainly the mycetomes, which house sup- posedly symbiotic fungi. The liquid squirted from the anus, and derived by Dufour from these glands, is obviously ordinary digestive waste, expelled by the contraction of the muscular rectal pouch.

8 . Physiology. One still frequently sees it stated in entomological works that

the rostrum is inserted into the tissues of prey, or food-p!ant, as the case may be. This is an entirely false assumption (see Myers, 1921 c). The rostriim or labium serves solely a,s a sheath, or in some cases (Psyllids) as x manipulator, of the set=. When the latter are deeply inserted, the labium must be shortened or else bent back a t one or more of the articulations. The former method occurs in cicada, where the setre a re not so excessively longer than the rostrum. The mandibular setre apparently retain tlie whole setal organ in position in the tissues, while the maxillary set% form the connecting channel. I n the salivary pump the retractor muscles of the piston draw back the organ,. causing saliva to enter the pump-cylinder from the duct-opening in the ventral wall. Thereupon the miiscles relax, and the piston tends to return to its former position by virtue of the elasticity of the strongly chitinous wall. This forces the saliva down the smaller of the two niaxillary channels, and thus into the food- tissue. Snodgrass (1921 a, p. 6) apparently missed this smaller passage, and was thus at a loss to understand that further pumping did not counteract the upward flow of tlie food-liquid. The function of the saliva remains still problematical; it ma,y be solvent or digestive, or both. Meek (1903), following Plateau, considers the second function predominant. Bugnion and Popoff (1908) consider that a diastase is present which dissolves cellulose


cell-walls and begins the digestion of &arch grains. The com- bined effect, by whatever method, is doubtless a readier flow of sap. The reaction of the salivary secretion, according to Plateau, .Bugnion and Popoff, and Kershaw (Cercopicls), is alkaline.

The sap ascends the larger of the two maxillary canals, under suction by the great pharyngeal pump, exercised by the action of it,s dorsal dilator muscles. Snodgrass finds tha t on relaxation of these muscles the anterior end of the pump closes first, thus ensuring the retention of the liquid ; and doubtless the second pharyngeal swelling, with i ts powerful dilators, acts in conjunction. The return of the dorsal wall of the pump would seem to take place by the elasticity of the chitinous supports and possibly by the chitinons dorsal rod, and not, as Muir (1926) suggests, by the reverse action of the dilator muscles, which would be hardly possible.

So much is fairly clear. W e have the sap, more or less altered, in the cesophagus. It enters the filter-chamber through t h e esopltageal valve, and the problematical begins. Berlese has suggested for the Coccid filter-chamber-the internal gland of Lubbock-that by its means the wat,er and the excess of sugars. in the sap may soak through the wcclls of the coil into the rectum and thus take a short cut to the anus, while the more nutritious matters follow, as usual, the whole course of the alimentary mnnl. Kershaw (1913, p. 177) notes tha t feeding the insects (in th i s case the Flatid, Xiphanta) on colonred liquids “tends to confirm this theory, since the contents of the long loop of the midgut are very faintly, if at all, tinted, whilst, die rectum is heavily coloured.” But neither of these examples deals with the t rue filter-chamber of the Auchenorrhyncha, as exemplified in Cerco- pidae and in a less highly-developed state in C icd ids . Here Licent (1912) has done some careful work, leading him t o adopt Berlese’s theory for these forms also, though he found tha t in Cercopidw a t least there mas no evidence of sugars in the liquid from the rectum; a.ncl thus he confines the action of the filter-chamber to the eliniination of surplus water. Yet it is well known that the liquid excrement or honey-dew of most other Auchenorrhyncha is rich in sugars. Rates describes tha t of an Amazon cicada as sweetish (1863, p. 227). According to Licent the astonishing thing is that the folds of the mesenteron, in the wa.lls of the filter-chamber, originally absorbent, reverse the action of their dialysing power and excrete the same water concurrently with the Midpighian tubules, with whose enclosed portions he found them in CercopidE to agree in the structure of the epithelium. Licent stresses the fact t na t the sap of plants is relatively innutritious-it must be taken in bulk. There is thus of necessity a rapid flow, showing itself, among other WR.YS, in the copions evacuation of watery material from the anus in most of these forms-an evacuation at times so profuse in the case of the Cercopiclae and Cicadida as to lead to the belief in “ rain-trees,” which water the ground beneath them.

452 DII. J. G . XI'XRS ON THE

Liceiit. believes that digestion m~oalrl he difficult were there riot some filtering device by wliiah the bulk of aqueous constituents conld be very qiiickly separated from t h e nutritious remainder.

To resume, t h e sap entering froin t h e cesopliagu:; is separa.ted by osinosis i n the fi1t8er-cliamber into its: watery constituents, wliich, perltaps :~ccoiiip~nietl by excess sugars, pass thimigli t h e wa.11~ of t h e intestinal coils a.nd s t ra ight ou t by t h e hinrl-iiites- tine, arid in to t,he more nutritious matters which pass along the lumen of tlie s t o m x h to entei. tlie long and tortuous loop formed by t>lie iriesenteric sac niirl by t h e inirl-intestine itself. This brings us t o tlie function of the huge and enigmatical inesenteric sac. Note first t h a t iti lies posterior to t h e filter-chninher, n . n d i s thus concerned, i f our theory of t h e la t ter be true, only with tlie more concentrated niitritious portion of t h e s ~ p . EIistologically, botli Licent and Hickernell found i t t o be lined wit,h digestive epitlieliuin, cha.ra.cterized hy '' nctivit6 skcrktrice e t absorbante," app'irentlv not less i n Cercopidp, wliere it is of niorlera.te size, t l i a r i in Cicadidx!, where it is very large, ant1 in TpphiocybidE, wliere i t is simply trenientlous. Were it largest in Cica.didq one woiild perhaps explain such developmerit as due to a function accessory to t h e auditory tyiiipannm (mirror) as claimetl by Vogel. This woiild then he a case slightly andogous with that of t h e Teleost swim-bladder, though in the Cicaditlx! t h e sac need not rrecesswily have lost so coinpletelj- i ts dimeit tary capcity. Hiit its still greater evolnt'ion in t,he a.ppnrent,ly silent Typho- cybids, i n mhicli, moreover, no auditory organ has yet been described, 1,enclers a, pradorninoritly gastrononiic explann tion more logical. 11 receive : i i r and t h u s act secoiirla,rily to ninintain normal :I pressure on tlie inner snrface of the auditory t ympnun i is rendered pi,ohable by t h e fact tha t i n Cercopid nymphs, accortling t o l ie rshaw (1914, p. 65) ,

" t h e air, mhicli d l sucking insects doubtless imbibe in qiimtity n.long with tlie liquid food, appears t,o pass through t h e alimentary canill nncl he utilizetl i n forming tlie air-bubbles conted .rvit,h mucinoirl which a r e eniitted front t h e %nus and form tlie frotli iit mliicli the nynipli lives. After examining this C'ercopirl, 1 ail1 the inore inclinecl to believe that . . . . t h e ' food-reservoir ' i l l t h e head of FZuta functions in p a r t a s an air-sepa,ra.tor to rid the liquid food of snperahundaiit a i r before i t passes t hroiigli t.h e a1 i 1x1 eritary caii a I. "

Th:it, tlie mesenteric sac may

Earl ier (1913, p. 179) t,ha same writer, tliscussing th i s food- reservoir af ter s ta t ing t h a t its chief fiinction, 011 account of its secretive activity, seems t o be digestive, says :-

'( It also collects a. quant i ty of a,ir, separateti from t h e food imbibed ; there i s always soyl1.e air, often ( especiailp just a f te r tile moult to adul t ) a very Inige amount."

NIORPHOLOGY O F THE CICADIDB. 453

Tliis food-reservoir of the Fnlgoroidea is not lromologous wit21 the mesenteric bac of the Cicadidae and Cicaclellirl~, though botli perixirl to the midgut. But physiologically, as in superficial appearance, they may have much in common. Granting t h a t there is some superabundant a i r to be separated from the food-liquid, i t r id supposing that this is not accomplished by the filter-chamber, then the air rnay be segregated, arid perliaps even stored in the cicacla’s niesenteric sac, atnd serve secondarily a s an adjunct to tlie auditory organ. In t h e silent nymph the sac is much less developed and considerably folded-the air may not be stored. In dissecting cicadas under wa,ter, one sornetiixes finds the sac to be full of gas, proba.bly a.ir. H u t such an enticing theory is to a large extent opposed by the still greater developnient of the sac in the Typlilocybids and other Cicadellids.

Le:tving the mesenteric sac, we find that the nes t section of the digestive tract---the mid-intestinal loop-is, according to Licent, botli absorbent and excretory. The proximal portion, u p to the constriction so well mar.lred in Cercopidz but obscure in Cicndirla, is almost entirely absorbent ancl digestive, while the part from there to the filter-chamber is excretory, like that within the latter organ. It also stores waste matter from the proximal portion. This would explain Hickernell’s(l923, p. 218)observation tha t in i V ~ , g i c i c ~ d c ~ septendecinz some sections of the ascending intestine (mid-intestinal loop) showed an epithelial lining of enorInous cells filled with granules, while iii others the walls were thin.

The Xalpighinn tubules, in so f::.r a s they enter into the filter- chamber, have been already discussed. The smooth, short, proximal portion (outside the filter-chamber), which in Cerco- pidz secretes the albuminous viscid material for imparting teiincity to the foam? has not been shown to be secretory in cicatla. !rhe familiar varicose, more distal stretches perform their nsua.1 excretory functions.

Tlic swollen excretory rectnm expels the liquid waste in the foicible iiiaunei so often rernarketl in the CicadidE, particularly in Er1rope:in species. It is extraortlinnry that l h r g i t t (1 923, p. 210) slioulcl actrinlly btate, with regaid t o septendeciin, that the adults “ leave no s i w s of excretory wastes, such as clefecx.tive prodncts,” anti deduce from t h i s t,li:it very little feeding takes .place in tlie iinagind star. This brings us to the subject of tlie next section.

c. Peediiig-habits. Two feature5 of cic:ida life, akme all others, appealed to the

imagination of the ancients. One was the lour1 ant1 piercing song, and the other concerned the mysterious feetling-habits. Few popular beliefs have taken so long t o die a s that which rtttri- butes to the cicada a diet of dew. Even Aristotle (Hist. Anim. lib. iv. cap. 7) saw nothing improbable in this “ alinientnni uiium

454 DR. J. G . NYERS ON THE

e t peculiare.” Pliny, of course, followed him, while Cardano, the physician of Milan, probed logically the nouiishing properties of dew, fiom the fact that it was the source of the manna nhich sustained the Israelites in the wilderness ! Hales. the English plnut pliysiologist (1 727), believed in the valuable properties of dew, which was absorbed directly by the plant.

To the question of manna produced by cicada-feecling punctures we shall return la te r ; but here we are impelled to quote from Donovan, who &as responsible for the charming English popular name applied to a Chinese cicada, namely “ Bea-locust.” Dono>nn writes that cicadas “ had been observed to fly among ash-trees, to re many holes in them, and when the manna had oozed out, return and carry it off.”

The earliest note I have, however, of cicadas feeding on some- thing if not more substantial, at least more nutritious, than the dew of heaven, is an obbervation made by Tancred Robinson in 1683 1684, but published in 1714-1716 :-

“ Coming near Cnpua, I ohserv’d a Species of Ash, or O m u s , on the trunk whereof many Saccharin Concretions were visible. This proved the true iWccn~a, tha t issues out thro’ the Incisions made in this tree h j the Iriliabitants of Ccdahricc. Swarms of Cicuclcc’s were sucking the Body and Boughs, and perhaps by wonriding them made way for fresh Manna.”

R8:iumur somewhat later (1740), describing the rostrum, says

L c Cette trompe apprend que la cigale n’est pas faite pour

and instances an observation of one of his correbpondents that a cicada, burldenly seized on a tree-trunk, often withdrew its mouth-parts from the bark only with great difficulty.

But the clew theory migrated t o America and held sway until compar~tively recent years. Potter (1839) claimed tha t CicadidE live solely on the exhalation from vegetable barks-“ the insen- sible perspiration of the vegetable skin.”

Hildreth (1830) saw the same species (septendecim) with its “ proboscis” inserted in the bark of a tree, and a drop of liquid exuded when the mouth-parts were withdrawn.

Jaeger (1 854, p. 102) retained the old fetish-“ they suck with their snorits only the dew of leaves.”

It is possible, although not proven, that we may have to recognize a difference, especially quantitative, in the feeding-habits of different species. Thus, in Europe, Y’ibicen plebeia, though well- known to feed (Fabre), appears to do so less frequently than Cicada orni, which was doubtless the subject of Tancred Robin- son’s observation, quoted above. I n Australia, Froggatt (1 903, p. 339) remarks tha t Cyclochila australasice! does not appear to feed in the adult stage. In North America it is usually the

(p. 474.)

(p. x) :-

vivre uniquement do roshe ; ”


periodical cicada which is given the palm for abstinence. Wi th regard to this species, there were stray observa.tions by Riley, by Davis, arid by March (1589), but it was Quaintance (1902) who proved that i t fed commonly, and sometimes in such numbers that the sap from the punctures was streaming down the trunks and branches of the trees.

Townsend (1892) saw Tihicen rnonteauma (Dist.) a.lmost certainly feeding on Yucca aizgustilfblic~

Gravely (1 91 5) had a captive specimen of Lem,uriana apicalis (Germ.) which fed on the sap of a piece of the tree on which it was caught. During feeding it emitted from time to time a jet of colourless liquid with considerable force from its hinder end.

This squirting of liquid surely is nn indirect proof of feeding. W e have observed it in iMelarnpsnitu c i ~ ~ y ~ ~ l a t a . The fluid dis- eharged is probably different from tha t emitted by the adult during the final ecdysis-a kind of moulting fluid (Davis, 1922, in Tibicen auletes ; Krumbach, 1917, in Y’. plebeia).

The feeding evacuations are specially numerous in CYicada orni (Krumbach, 1917) ; in PZatypZeura capitnta (01.) (Pacilopsaltria subfiufu Dist.) (Biscoe, 1896) in India ; andEhave been described in an Amazon species (Bates, 1863, p. 227). In Australia, Psaltoda marens (Germ.) feeds continually on the trunks of Angophora lanceolata, emitting meanwhile a spray from the anus (Froggatt, 1903, p. 340).

The most copious rain-makers are, however, reported from Mexico. Dr. W. M. Mann found that in one new irrigation district a main ditch was being constructed with an angle t o avoid a rain-making tree which was considered almost as valuable as a small irrigation system, and far cheaper. An undetermined species of cicada. was thickly perched on this tree, busily producing the ‘‘ rain.” An exactly similar tree with cicadas is recorded, lilrewise from Mexico, by Krieger (1904). This writer found tha t the evacuation WRS performed with a chorus effect, much like tha t observed in the song of the other species.

“ Beginnt eine der Cioaden ihren Tropfen z i i schleudern, so ist dies das Zeicheri fur die ganze Gesellschaft, eingleiches zu tun, untl in wenigen Sekunden ist die Ersclieinung des Baumes, der nach Belieben regnen Iasst, fertig.”

I n the case of some species, at least, it would appear t ha t no very great restriction in feeding-habits is shown. Thus orn i , which seems in some districts to prefer ashes and olives, in others haunts pines, and Siwinton (1908, p. 380) found it in Spain feeding on especially resinous ‘‘ mushroom-topped pines.” He was “at liberty to pick as many of the intoxicated bridegrooms off the sticky trees as I pleased, for they had drunk the spirit of turpentine, which is a poison to Man, long and deep.”

456 DR. J. 0. MYERS ON THE

e . CIRCULATORY SYSTEM.

The t1ors:tl vessel or heart stretclies practically the entire length ot the abdomen with a conipartinent in nearly every segiiient and the usual lateral muscular wings (test-fig. 71). The first or most anterior of these compartments is largest and almost circnhr. It is situated in the Ilncl segment, and sends f o i ~ ~ a r ( I the aorta, which reaches thus from the I Ind segment to the Iiead, p s s ing between the great lateral thoracic muscle-masses. Thence i t threads the folnmen between the esophageal connectives, and lends above tlie cesoplragus to the posterior smelling of the pharynx, where it eiitls in an open mouth in close relation with the bases of the posterior dorsal dilator muscle of this orwn.

h e aorta is colourless or white. while the heart, itself is dnrk- coloured-at least in alcohol material of Cari?~utcc jomzosa.

f . FAT-BODY. 1.he fat-bo?ly, representing a tissue rather than an organ, mas

first considered in Cicadidae by Dufour (1825), who described it a.s glnmcoiis-green in coloiir and most beautiful near the end of the abdominal c:tvity.

I t is cliffuse and plentiful in nymphs and in adults of both sexes, especi:dly in the abdomen. It is permeated by trachete ant1 trncheoles, and biricls in sheets the intestine and Malpighian tiihes. The niesenteric S:LC has a. capc i ty for adhering to it wherever contact, occws, and sepmxtion is extremely difficult mit31iout i*npturing tlie thin walls of the foriiier.

Comstock considers i t i s tlevotetl primarily to tlie storage of nutriment and secoritla.rily to excretion. It plays a n interesting rdle in the cicnt1:i.s arid otlier Homoptera in snppplying housing to the sup- poseetlly symbiotic Saccharomyces. According to American observers, infection by the fungus, Jlcissospolol.a cicadiiza, which C:LII jes such :I. heavy mortality among males of septeiadacim, increases with tlie retluctioii in the fat-body during adult life. Is i t pssible tliat there is ail antn.gonisni between the Sacclmro- niyces a r i d hlre ilfwsospora spores ? Mrilc lins already suggested a bactericidal fnnction for the symbionts.

r .

The function of the fat-body is probleni,ztical.

g. REPRODUCTIVE SYSTEM. The so-called " genit,nlia '' or appendages of the reproductive

systeni have been tre:itetl with the chitinoris skeleton generally in :t previous section. This leaves 11s with tlie gonads themselves- organs with which few observers h v e concerned themselves. As i r i so iiiany other feutures of internal anatomy in the Hemiptera, we t u r n to Dufaur for the Grst thoroughgoing study of these 0 rgan s.

Our oirn observations have been mnde chiefly upon the neotropical CaTineta fomaosrc.

YOItPI-IOLOGY OF THE LICADIDX. 457

a. Jlale Beproductive Oigans.

Apparentl) the first account is t h a t of Meckel (1808, pp. 5-7, figg. 2-5). H e states that the median swollen ejnculatoiy duct appears to be glnndular ; its inner surface is befet with small openings. Tlie figures illustrating conditions in Tibiceiz ( l ’ e t t i - gonia) plebeia sliow the testes, their ducts, one pair of thick and long accessoiy glands, the ejaculatory duct, and the adeagus.

He describes the geneial relationships with detail and accuracy. I ivo nccessoiy glands were found, and considered a s seminal vesicles. The ejaculatory duct is desciibecl as swollen nt the base.

Ueilese (1909, p. 856) copied Dnfour’s figure, hut added little to the FI ench author’s account, which iemains the best extant.

J n Cayineta forrnosa the two testes are ioumhly spherical, but at the same time diffuse (text-fig. 72, t.). %he vas deferens from each is extremely long and complexly coiled (wd.). An apparently equally long and veiy much thicker accessory gland of iinknown function opens with it into the base of the conimon ejarulatoly duct; bu t just before this fusion the vas deferens and accessoiy glanti together form a small swelling which niay be considered a vesicula seminalis (vs.). The proximal portion of the ejaeulatorj- duct is inordinately swollen and furnished with thick walls. Berlese names it “ ampolla eiaculatrice,” while Apgar (1887) mistook it for the “ single testicle.” Between this organ zinc1 the base of the Edeagus the ejaculatory duct (text- figs. 34, ej., 72), while still stroiig, is of sinaller calibre. It enters the :deagns by the basal foramen.

The greatly-developed accessory glands WOlild seen1 to be nzesadenia, i. e. formed froin the mesoderm, but observations on development are Iacliing to establish this.

Unlike tlie external genitalia, the gonads, especially in the male, :we apparently very similar througlioiit the family.

Dufour (1833, p. 186, sep. pag.) deals with Cicada o&.

r ,

a. E’ewac.de Z?epodzcctive O r y a m Meckel (1808) dealt with tlie feiiiale as with the male gonads

in l’ihicen plebeia. H e was the first to describe the single long, thick, unpaired, accessory gland opening near tlie apertuie of tlie vagina a t tlie base of the ovipositor. He states that thi4 gland nrisps from a swelling whicli give5 iise to two tiibes,one the iiecli- of the spei-nmtheca and the o?ller the conimon oviduct. Tlie latter branches into two pairs of canals--one those of the prirecl accessory glands and the other the ovidncts. Tlie paired glands seem to contain the same matter as tlie impaired.

Dufonr gzve a detailed description i i i 1825, recognizing two lorlg vessels secreting (‘ sebaceous liuniour.” The whole account IV\V&S modified in 1833, and, among other matters, three of these vessels were shown. They aie described as being half a s long as the insect, membianous, senii-diaphanous. Their positions ni e

458 DR. J. 0. WYERS OX THE

as observed by Meckel. In the figure (188) the spermatheca is labelled as the reservoir of the sebaceous gland.

DoyAre (1837 6) studied the parts immediately adjacent to the base of the ovipositor in great detail, in ~ ~ c u d a nzunnifera (Fabr.). (=Fidicinu 172.). H e described what he believed to occur during copulation, stating tha t the penis proper finds i ts way into the diverticulum, which he called poche copulutrice. H e discovered the small vesicles on the neck of the latter and the long fillform tubes which Gadd (1910) thought had escaped all previous eyes. Doyhre noticed tha t these vesicles contained a fatty substance of a yellow colonr, evidently secreted by the hair- like tubes. H e found the tubes themselves to be five to ten times as long a s the body, and confirmed the presence in this third species of the three stouter accessory glands of Meckel and of Dufour (1833).

Holmgren (1899) used Cicadellids, Cercopids, and one Fulgorid in his investigations of the female reproductive system, but made a comparison with DoyBre’s and with Dufour’s results. The chief point of difference appeared to be the lack of the paired accessory glands opening at the junction of the oviducts.

Herineguy (1904, p. 166) remarks that the poche copulatrice receives the Semen in Cicadidae, and this is then stored in the receptacula seminis, of which the cicadas possess two (p. 169). This is surely an error, unless the latter name is applied to the small tesicles on the neck of the bursa.

Berlese (1 909) fails to mention the unpaired accessory gland, but otherwise follows Dufour closely.

Gadd (1910) studied the female reproductive system in Tibicem plebeia. Cicnda orni, Cicudatru querulu, C. atru, C. hyalinu, Melan~psaltu udustu, and &f. nzontam-seven species in all. I n all he found the unpaired gland first described by Meckel, and noticed tha t in plebeiu and orni it is very long, reaching to 20 mm. in the former, mhile in Cicudutru i t is reduced, and in iMelurnpsulta much shorter than the oviduct. This may therefore explain my own failure to find it in Nelanzpsultu and in Carinetu. Similarly, the efferent canal of the 1 eceptaculum seminis in both Cicudutru and Melunzpsulta (Cicudettcc) is proportionately shorter than in orni and in plebeiu. Gndd claims the discovery of the paired filiforin glands opening into vesicles at the entrance of the receptu- c u k m senzinis. W e have seen, however, that these were accurately described by Doyere in 1837. Gadd’s receptaculuna senzinis is evidently our apical pouch (text-fig. 75, up.).

In Curineta there are, as in other species known, two large ovoid ovaries (text-fig. 73, ow.). These contain in a European species 70-80 ineroistic ovarioles, according t o Berlese. The number in Curineta seems t o be of the same order.

The oviduct (text-figs. 73, 0.) bends shortly and runs t o join its fellow and form a stout, short, cominon oviduct or vagina (text-figs. 73-75, co.). This bends over very sharply near its beginning, and just after the union of the oviducts receives

MORPHOLOGY O F THE CICADIDX. 459

a long, winding, accessory gland from each side. These appear homologous with the very similar structures in the male, but are shorter. They can, of course, be considered neither spermathecal nor colleterial glands, and their function remains for the present unknown.

Near the external opening the vagina receives a large sac-like spermatheca. Comstock (1925, p. 160) remarks tha t a bursa copulatrix is said t o be wanting in Hymenoptera, Diptera, Heteroptera, and Homoptera, except the Cicadas. I am not clear to which organ in the cicadas Comstock would apply this term. There is only one large sac-like appendage to the vagina in this and in other recorded species. This appendage, the speinatlieca, shows, however, a differentiation very marked, into a relatively soft-walled apical pouch (ap.) and a very stout and muscular portion proximally (ms.). Possibly the latter subserves the function of bursa copulatrix, but we are here calling the whole organ a spermatheca.

A t each side of the entrance of the spermatheca (or bursa, Comstock) is a tiny thin-walled sac receiving a long, much coiled, thin, and thread-like white gland discovered in other species by Gadd in 1910 (text-figs. 73-75, acs.). These glands, which are cut short in our figures, are to be considered as spermathecal glands.

Finally, as to the large, very long, unpaired gland opening into the I agina near its orifice, as discovered by Dufour and confirmed by Gadd (1910), bu t omitted by Berlese (1909, fig. 1132) from his copy of Dufaur’s figure, I have found traces neither in Cariszeta formosa nor in Melarnpsalta scutelluris ; but the condition and quantity of my material hardly warrant the assumption that it is therefore absent in these species. Gadd found it very short in Nelcc?npsalta adusta.

I n Melampsulta scutellccris the filiform sperniathecal glands are thicker and somewhat shorter than in Carineta. The vesicle on each side, into which each opens, is larger than in the other genus, translucent and bright yellowish-green instead of white as in Carineta.

(3) SOUND-ORGANS. W e now come to those parts of cicada anatomy which, above

nll others, have enabled these insects, in more senses than one, t o make a noise in the world. W e have here to deal with the most complicated sound-producing organ in the animal kingdom-and one which usurps such a large part of the cicada economy as to remind us forcibly of Plato’s story tha t these insects were once men who gave up their whole lives to song, neither eating nor drinking, and singing, died.

The following comprises, firstly, a description of these organs as they occur in Melampsaltu, notes on their mechanism and a discussion of the further specialisation exhibited by the Platy- pleurinz, and a few notes on the condition of the corresponding

460 DR. J. a. MYERS ON TIIE

parts in females and nymphs ; secondly, a. historical review of our knowledge of c i c d a sound-organs ; and, thirdly, an account of the accessory strirlulating apparatus of the subfamily Tettigadinze. It has been necessary to depart from historical sequence i n this arr,iiigeiiieiit, since a description of the organs is a pre-requisite to :L just evaluation of enrlier contributions to their morphology.

a. DEACRIPTI~N OF SOUXD-ORGANS. 16-23, 27-29.)

(Text-figs. 10, 14,

Unless otherwise stated, the description is Lased on New Zealnritl species of ilfelasnpsalta, chiefly sericecc and nztcta. An effoi t has been made to stabilize the terniinology,

1. The opcrczda are two large plates on the iinclersicle of the body, extending posteriorly from the inetathorax and covering a large ventral cavity. I n Afelonapsultffi they are short, in Lenabejo (fatdoqua) and in l’ettigccrcta entirely absent, but in some species of the Oriental Dundubiini-in many respects the most liighly specialiLecl of all czicadas-they are extraordinarily elongated and attain nearly the apex of the abdomen. Text-fig. 10, if nothing else, shows that these organs are extensions of the metathoracic epiniera, a h statecl by Carlet. Mayer (1877) arid Prochnow (1907-8) consider them episteriaites. Comstock calls them outgrowths of the sternella, but in septendecina they may be seen distinctly to curve round the metasternum, which itself bears a projection (apophysis of Carlet) for the insertion of the folded membrane. Tlie opercula are the volets of Re‘auiiiur, Carlet, and F,ibre. They have been inexcusably mistaken for the agents of souiicl by several t‘Lxonomic writers ; thus Francis Walker calls them the drums, and ;Lpplies the term opercula to the lateral coverings of the tynibals in P la typleur in~ .

Projecting over the base of each operculuni is a nieracanthus which BBanniur (cheville) believed to function as a lock to preveiit the operculum from moving too far from the plane of the abdomen. But the operciilum is immovably attached to the thorax, ant1 the space between i t and the abdomen, which in some species is varied during singing, is altered by lifting the nbtlonien from the operculum. The effect, of course, is the same. The opeicula are moderately developed in the female.

2. Tlie ccczlity-the chzcr.ch or la gleaso of tlie Proverigal peasant -1ir.s beneath tlie opercula. It is bounded anteriorly on each sitle hy n yellowish fo lded m e ? ~ z ~ ~ a ~ z e , nirich is apparently the intersrgniental mcriibrane between the thorax arid abdomen, :lnd posteriorly by a naiwor, which has already been described as the tyinpniini of tlie chordotonal organ lying in the lateral wall of each I l n d ab~loniiiinl segment. The mirror has usually been consi,lered ( e . g. by nllayer, 1877) as the intersegniental menibrane between the Is-t and Ilncl abdominal segments. but Vogel, as we sbd l sep later, sees in it the “ PlPzcralhcczct” of segment I. Apart from the opercula, tlie mirrors are the only organs of this

NORPHOLOGY OF THE CICADIDB. 461

complex which are present in the female. The folded membrane is probably only of articulatory importance ; but Carlet describes a sniall tensor muscle, and believes the membrane is an accessory vibratory structure, a character as5ignetl also, by assnnipt,ion, t o the mirrors until they were recognized as the tympana of the auditory organs. Vogel describes also (1923, Abb. 5 ) a tensor muscle of the mirror, but I have been unable to find a n y trace of this in Nelanzpscclta (text-fig. 27).

3. The spiracles associated, in our opinion only topographically, in that of other observers (Cnras, Lanclois, Swinton) functionally, with the sound-organs are tlie third and fourth pair (first and secoiitl abdominal). Their position has already been described in section (2) c. of tlie present paper. W e have seen also tha t the t,achecd sac of many observers is mesenteric in origin and has no communication yet proven with the spiracles. Some writers, concerned only with the sound-organs and dissecting probably dried material, have not even recognized a sac, but speak of the third spiracle as opening directly into the body-cavity (Carlet, 1877, p. 20, in Tibicen plebeia). Vogel claims that the mall of the sac is fused with the tyiripnnuni, the two together forming a wall only 0.5 p. thick ! 4. W e have reserved till litst the effective instrument of

sound. All the foregoing stroctnres are mostly protective and accessory. The sides of the 1st abdominal segment show as tergal modifications two convex, 0 ~ 3 . 1 ~ strongly-chitinizecl, pale- colouretl ph tes in a, franie even more stoutly chitinized. In dfelc~nap~alta the surface of each tynzbal shows usually a posterior smoother portion with one strong rib at its edge arid an imterior with strong, more or less parallel ribs, slightly oblique but, not far from perpentliculnr t o the long :]xis of the cicada body. These ribs are darker in colour than tlie rest of the tymbd. I n JiCcbgicicacZcc there is ft greater development of parallel ridges and less smooth space. The tgrnbal of l ' ih icen chZoro?iaera is more like that of Xeelanzpsalta.

5. Dissection is necessary to lay ha.re the musculature which pnts these organs in niotion (text-fig. 28). It is convenient t o cut off the abdomen at about the IIIrd segment. I n ca~~clal view the mirrors w e then very conspicuous, and the other orga.ns may be seen throiigh them. Prominent among the latter is a large chitinons V, standing on the sternal surface mid reaching its ~ r i n s u p almost to the tlorsum. TIiis is the triangle Bcccilleux of R&:Lumur and the e~~tngastre of Audouin and Carlet. The whole or pitrt of this structure has been hoinologisecl incorrectly as the fiwcn of an a,bdominal segment, interpreted either as I. or 11. We shall consider its true nature in the seqneel.

Parallel but dorsal to the a,rms of the V, and inserted in aviclge in the ba.sal portion of each, are two large muscles-the lmgest single muscles in the body. These are the tymbaI-muscles. Each brindle enrls distally in a chitinous plate-XehneizpZatte of Togel,

PROC. ZOOL. Xoc.-l928, No. XXXI. 31

462 DR. J. G . JIYCRS ON TEE

plapzce caTtalaginezLse of RBaumur, kpiclhe of Audouiii, d i s p e t e rnb id of Carlet,-from which R narrow tendon extends to its attachment in the doisal portion of the inner face of tlie tyii ihl at the main ridge of the miootfler portion (test-fig. 28).

2'?~7iLbcil-covei-s. --We have described the complete bound- pioducing apparatus as it appeals in its simplest foini. I n the Vlntyplenririre, to which subfamily belongs Tibiceiz plebeia, the species most often studied by European woikers, tlie tymbalz are coiiipletely hidden from view by a forward lateral expansioii of the second abtlominnl tei gite, which forms on each side an accessory cavity of which the inner mall is forniecl partly by the tymbal. These second cavities-cellules of Ri.auniur, cavernes of Dug&+- are niucli narrower but considerably deeper than the main one bonndecl by the opercula, folclecl membranes, and mirrors. I n the subfamily Cicadinw (Gsminse Diat.) the tyiiibal covers are incon~plete.

The essential elements of the sound-producing apparatus are the tyiiibals and tlie tymbal-muscles. The experiments of Laurentus (Zanotti, 1731, p. SO), of Lepori (1869), of Mayer (1877), of Solier (1837), of Goiireau (1838), of Medici (1847), of Lucas (1887), to mentioii only N few, all attest the fact that the destruction of actual or supposed accessory parts-opercula, folded membranes, mirrors, " tracheal " sac-and the stoppage of the adjacent spiracles have but the slightest, if any, quantitative effect on the production of sound in the living cicada. Landois's theory that the third spiracles were tlie instruments *lf sound never had the slightest experimental foundation, but, on the other hand, went against all previous evidence. The more reasonable belief of Carus and others that the spiracles acted as accessories by supplying the air to the " tracheal" sac was based 011 observations made on l'ibicerz plebeicc while singing. This species, like several of the New Zealand me lamp salt^, modulates the sound by alternately widening and narrowing the entrance t o the main cavity by raising or lowering the abdomen. This rhythmied movement was mistaken by Carus for a respiratory one. I n those species, like Jlelffinysnltcc nzuta in New Zealand, which do not thus manipulate tlie opening while singing the song is nniform and monotonous, though the volume of sound is no smaller.

The former are convex, and if they are pulled inward and released by nianipulation of the appropriate muscles in a moist specimen, they will regain their former convexity by virtue of the elasticity which resides especially in the strongly-bowed ribs. This process is accompanied by a short click like that emitted by a t in call similarly indented-and these clicks, rapidly repeated, constitute the song of the cicada. No further arrangement is required. But the simplicity of this explanation, first clearly demonstrated, though not discovered, by RBaumur, has been repugnant t o several investigators, and Graber would see in the sound a result

W e nre reduced, then, to the tymbals and their muscles.

SIORPIIOLOGY O F THE CICADIUB. 463

of friction between the rib5 of the tyinbal during the alternate moverrierits of contraction a n d relaxation. Hingston 11922) carries this idea still further-believes that the click elicited by inniiipulntion of the apparatus in a dead cicada results from the tapping of a tooth boine by one of the ribs on a bar which corre- sponds with another thickening. Since the tymbal sti ucture iir’cessery for this method is fay froni general in the family, and i i i ~ y be even coilfined to the one species studied by Hingston, thi5 esplnnntion, even if partially true, is too limited to apply to cicada music as a whole. So far as we can bee, in n deacl specimen of l’ibiceiz c/~~o~o7irercr the inovenlent of the tyinbal is just a simple buckling on a line near the middles of the chitinous bais, and allnost parallel with the long axis of the body.

C‘iilet attempted (1877) to measure the vibrations of the tyinbal by fixing a fine ghss thread with wax to this organ and plaririg the other end of the fibre in coiitact with a revolving cylinder fnrnislied with a smoked surface. The experiment was riot 1 ery successful, largely because a captive cicada never sings “ pioperly,” but eniits an alarm cry like that of a bird under similar cii curiistances.

The same observer (1876 b ) observed that tlie tymbal-muscles contract aimultaneously.

It is needless to state that the sound-organs are confined entirely to the males. Apparently Amyot (1836) was the first t o make the statement that certain unspecified exotic forms had the sonnd-organs almost as well developed in the male as in the females, and that presumably these females sang too. Although this seems to he entirely incorrect, it has been repeated in several reputable works, even as recently as 1909 (Berlese). Girard (18613) states the belief very dogmatically.

Ilouaologies of the ASo~nd-07-gans.--The interpretations offered towards the solution of the homology of the structures involved in tlie sound-producing apparatus are confusedly various. The following points zwe, however; agreed upon by almost all workers :-

a. The tynibais are modified portions of the first abdominal tergit e.

6. The tymbal-covers in the PlatypleurinE are outgrowths of the I I n d segment of the abdomen.

c. The folded nienibrane is the modified interseginental membrane between the mietasternum and the ventral part of tlie abtlornixial base.

It niay be further taken as established, in spite of assertions to the contrary, tha t the following homology is substantially correct :-

cc. The operculs are productions of the metathoracic epimera only.

31”

464 L)R. 3 . G. XYERS 0s THE

b. The mesenteric (so-called b L tracheal”) sac is primarily a part of the alimentary tract.

The most important of the remaining questions concern the origin of the furca-like structure snpport,ing the tymbal-muscles, ant1 of the mirrors or auditory tynipxna fastened along one of its edges. I n the solution of these problems it is possible tha t a dissection of Tettigarctcc, which is devoid of sound-organs, wonld be of assistance. Scarcity of materid makes this impossible a t present, hu t an external examination shows the following. concli- tions in the adult mnle :--The opercnla are conrpletely lacking ; there are not even the rudiments seen in the females of other species. The 1st) abdominal segment is greatly reduced, but shows 1:r.ter.nlly a slightly swollen area, free from the long Iinirs which thickly clothe tlie rest of this region, and furriislied with faint ridges. Were not nearly ,211 the other ch:tracters of Y e t t i - gaisctcc a.ppxrently highly primitive, one would be inclined t,o see in tliis structure the last vestiges of tynibals lost in the history of the race.

Herlese considers tile, chitinous V in question to be the furca of the second abtloininal sternite (p. 707) or of the first (fig. 633) -an inconsistency not unusual i n the 1tali:~n worker’s gre2.t boolc. C‘onistock (1 925) agrees with the first honiology, while Ininis (1925) states tha t the tynibal-muscles arise from tlie “ mesofurca.” Tho two authors, however, who have given the matter the most a.ttent,ion a,re Carlet (1877) arid Vogel (1923). The former sees in the structnre in qnestiori an endoskeletal developinent of the 1st abdorninal segme:it: and calls i t the ento- qccstre, while Vogel likewise ascribes it to segment I., :I. conclusion which, as we shall see, there can be no disputing.

All previous workers Iiave studied the honiologies of the soiind- organs only in aclnlt males, with an occasiona.1 glance at a female, Init we have attempted to follow a developmentnl series, beginning witii a feirinle nymph, as likely to contain the least rudiments of tlie :Lpp:tratiis, then studying the male nymph, the atlnlt female, a.nd then the adult male. This has been done witli those species Q€ \\-liidi w e liave sut>hentic niat,erial of the pre-imaginal stages-- n:i.iriely JIelrcmpsrcltrc Ieptomera, iW. serierc and iK. ciit,plccta, and ilItcyicicatlcc septendecinb.

1. Tlie female ultimate nymph shows the first sternite greatly reduced-iii fact :dmost obsolete. 1nfern:~lly there is a power.fii1 furcn from the metasternam, but iiot tlie slightest trace of enclo- s1ielot:tI structure in a.hc1omina.l segments I. nnd T I . (text-fig. 22).

2. The male ultimate nymph shows snr~prisiiigiy little dif-fer- ence from the feninle condition. There i d , however, a raised dome-like area of smooth, white, very thin skin where tlie tynibal \vill lie on the 1st :rbdoniinnl segment. This is so laige as t o suggest tha t the arliilt orgmi owes its structure and strength la.rgely to excessive folding of this area. The rudiment of the hearing-capsule is more swolleii than in the female. Tlie

There are no signs of a mirror.

NORPHOLOGY O F THE CICADIDB. 465

boundary between segments I. am1 11. is ra ther indistinct, and, a p r t from the a.nditory capsule, very membranous. Them is n o ,iiLoYe trace of ccbdonainal fiwcce here than in the female of corre- spoiiding a g e , while those of t h e thorax are distinct and well developed.

3 . ln the adul t female (text-fig. 20) t h e nymphal condit>ions liave been iiiucli modified, especially i n nbcloiiiiiial segments I. imtl 11. The chitiiiized part of tlie 1st s teni i te (test-fig. 14) is very sniall. The inii.ror has come in to being, bu t i s much sniallei- t1i:tii i n t h e rnxle. Its front border is formed by a narrow chitiiiizetl piece. Its hind-border arises distinctly from t h e 1s t steriiite :i,s a chitinous s t r ip which, as seen from within, runs into t h e 2nd sterni te and seems t o be continuous with t h e posterior margin of a flap folded back on t h e 2nd sterriite (text-fig. 20,3.), along tlie intersegmentrtl line. The lower margin of the mirror

W e shall see la ter whetlier the flap itself belongs really t o I. or II., but t h e fact is assured t h a t t h e mirror lies wholly i n segment I., and consists of n tliinniiig of t h e sternite itself, as Vogel (1923) was appwently t h e first to recognize. Xoceover, t h e line separating I. from 11. p:i.sses between the 4 th spiracle ant1 the anclitory capsule, and the fornier inust therefore be considered as topographically belonging to I. There is n o sp i~xale n.ctually situated OH seg- inent 11. If I-leyinons and others ~ h o believe there is a foi.n-a,rd shif t of syira.cles (luring development in th i s region a.re correct, theti spiracle 3 belongs to n.hrlomina.1 segment I., but lias moved on t,o t h e posterior edge of the meta.tlior:ax, while spiracle 4 lias made R siniilnib shift from 11. t o I. If, on tlie other hand (see section (2) c. of this paper), these workers a re wrong, and spiracle 3 k)elongs t ruly to t h e tliorn.x, as i ts s t ructure mould seei i i to snggest, we are faced, wlietlier 4 belongs primitively t o .I. 01' II., with t h e ariomalous conclusion t h a t a spiracle occiipying : ~ n intermediate position i n tlie series has been lost elltirely. W e prefer the former explanation. Vogel believes t h t t h e line sepal-itting t h e m e s d border of tlie mirror from t,he chitinized niesal part of sternum 1 is Ironiologoiis with Ifeyiiions's eiiibryonic division between s terni te and parasternite. !C]IIIS t h e iiiirimrs woulcl correspond with the pamsteriiites of segiiieiit I. Tile ratlidity of this division as :i.pplietl to :~.dult st1,nctiire is, liowever, very questionable (see section (1) e . of th i s paper), arid we prefer t o reg:trcl t h e auditory t,ynipnnum merely :],S a, t1iff'erenti:ttetI par t of sternite I. without conimitting onr- selves t o its homology with a more or less liypothetic~~.l para- s t tw in .1 segregate.

There is no sign of endoslreletal s t ructure in tile female abiloniiiia,l segments I. rid 11.

ched t o t h e posterior edge of th i s fiap.

Turning now t o tlie a.tlult male (text-fig. In), we can understand t h e position bet ter by coinparision mitli t h e feniale. The small stroi~gly-cliitinizecl 1st s terni te of t h e feiiinle is here nierely bent

466 DK. J. G . MYERS ON THE

more slmrply upward on each side, and continued into the fore- rim of tlie mirror in accordance with the much greater derelop- ineiit of this organ. I n the male this fore-border is inuclr wider, stronger, and more wing-like (text-fig. 29)? arid extends, as in the felil:~le, to the neiglibonrliood of stigma 4 ancl of the lower corner of the tymhal-i. e . to tergite I. Thus this winglike fore-border is really part of the outer body-wall of tlie 1st segment, and, in fact, merely a differentiated part of sternite I. There is nothing really endoskeletal about it-yet i t is an arm of the IT wliich has been called the fnrca, of the I Ind sternite. A glaiice at text-fig. 29 will show that it belongs entirely to segment I.-tlie line of demarcation is clear. Anterior to this diEerentia.tec1 part of sternite I. on each side lies tlie folded membrane, ancl posteriorly the mirror. If we accept the para- s t e ~ n i t e coiiception, then this wing is part of parasternit'e 1. along with the mirror. All t1ia.t has happened is tha.t the entire lntero-ventral portions of sternite 1. have been stxorigly con- stJricted--pashecl dorso-mesa.lly, so as to leave a resonatory c:3.vity between what, is really the ventral surface of segment I. a.nd the opercnla, which lie in the normal plane of the venter. No encloskeleta.1 structure lias been produced since the whole of segnieirt 1. lias participated in the change. The tergite has supplied the tymbal on each side, while the sternite has differen- tiatetl in each lateral region into a strong chitinous anterior portion serving as a support for the greatly thinned posterior part or mirror. Text-fig. 89 shows that there is a slight inward buckling near the base of the two sternal wings in septendecim. The two parallel ridges formed thus, one on each side, tend t80 approximate each other. They are the nearest a,pp~o:~ccli t.o endoskeletal strncture found in this segment, and t,hey serve as the fixetl insertion of the tymbal-muscles. I n Tibicen c h l o ~ o n ~ e r a these ridges a.re better developed and practically meet, forming a strong caxina perforniing the same function.

The hind edge of the mirror is formed, as in the female, by a stron~ly-chitinizet1 flap a,pparently from the 1st sternite, folding over within the nnterior edge of t.he 2nd sternite, thus making a strong reinforced rim. Whether this flap itself (text-fig. 20), cnrving ba.cliward and inward over the edge of the 2nd sternite, belongs t o segment 11. or to segment I. is difficult to decide. The 1st segment sepmates easily from the IIi id along the inter- segnicnta.l line in KOH preparations, and the tear always continues right along this fold, thus separating the flap in qiicstion from segment 11. Rut along the fold there is no sign of n ten1 suture"text-fig. 21), ancl, moreover, the posterior sternal wings (text-fig. 29) a.re not continuous with tlie flap, as viewed from within. A t the lateral or dorsal extremity of the fold, on the other hand, the chitin is continuous.

This questlion, however, does not aEect tlie conclusion tha.t the wliole of the sound-producing apparatus, together with the tympn nil. of tlie chordotonal organs, belongs to abdominal segnient I.

MORPHOLOGY O F THE CICADTDB. 467

To the homologies already tabulated a t tlie beginning of this subsection we should therefore like to adtl the following :-

( r . The wings of the so-calleclficrc~(Eerlese, 1909, figs. 433, 882) supporting the tynibal-muscles at their base are not endoskeletal, but are rlifkrentiatecl anterior parts of the 1st sternite.

b. Tlie mirrors or tympana are differentiated posterior portions of the 1st stprnite.

c. Tlie whole of the sonncl-organs pertains to segment I.

b. RISTOI~ICAI, REVIEK. ‘i‘he first Irnown observation on tlie methorl of sound-production

in the Oicadiclze-that of llesiod, about the eighth centiuy before Christ--we have seen to be :iccurate so far a s i t goes. The tettix ‘‘ pours forth from under his wings his shrill song.”

Arist>otle’s much later and more detailed account, a n extensioii, so far as tlie scientific equipment, of the time would allow, of Hesiocl’s observation, w a s the first ibttempt at a formal explanation. The relevant passages (Hist. h i m . , lib. iv. cap. 9 ; De part. anim., lib. iii. cap. 161, tilough sliort, have given considerable trouble to the corrimentators The following iriterpretn.tion is based on the various editions and comnientn.ries cited in the bibliography, and on the exegetical notes of Lnriclois (1 867). The explanation involves Aristotle’s conception of respiration, ~vliicli he regarded as essentially a process of cooling. Vertebrates accompli,cli tliis result by taking air into the body and expelling it, a,gain. Insects do not breathe in tliis sense, but achieve the same end by tlie a.gitation of the air enclosed within their bodies. By this nioveirient the body fluids :we brought into contact at tlie hyposorrzn with tlie thin menihrnne which there sepa.rates them froin the cooler outer air. Ogle and Landois tliinlr that the hyposonia is tlie waist-line o r septum between thorax arid abdomen in its veritrnl part. In Bies, bees, and similar buzzing insects this sound 1s produced by tlie vibration OF the membrane at the h?yposonzn, brought about L i attritu s p ~ i t z ~ s . ” I n those tettiges which sing, the liyposomatic insinliing is rnucli more greatly developed, but the song is pro- clncerl in the same way. Landois compares the agitation of the ‘‘ innate spirit ” (Ogle) mith the nioveinent we might impart t o the air in our chest by moving our dinphragm up and down while keeping the nostrils :tnd lips closed. \Ye do not think Ogle’s above tmnslation for rrve6pa is well-advised, for Aristotle apparently meant the term to connote merely enclosed xir mith- out any metaphysical iniplications. The movement was conceived as produced by relative motions of the internal organs.

Snch was the explanation which held sway until after t he Renaissaiice. It possessed the merit of distinguishing clearly between the song of the cicadas a.ncl the striclnlation of Ortho- pteroids; and it was as definite a s the biological concepts and scientific equipment of the time would allow. The absence of

We must exaniine i t :L little closer.

468 DR. J . a. JIYEHS ON THE

even the riidirnents of knowledge concerning muscular action on tlie one liniitl and respiration on tlie other, i n invertelurntes, inacle i t impossible to distinguish i n prirjciple tlie song of t h e cicadas and t h e biizzing of bees and flies.

The two other main t.heories of cicada souncl-prodiictiol1i atdmnced i n classical times a re superficia.1 i n comparison. On t h e one hand, illeleager, Apollonides (or Philippus j, and other writers i:i tlie Greek Anthology, by confusion with Orthopteroid st,ridu- lation, spoke of such methods a s “bea t ing i t s belly with i t s wings,” ‘‘ striking i ts feet with its wings,” or its body. On the other hand, was t h e idea, apparently Egyptian, thougli mentioned also I)y Bia.nor i n tlie Greek Anthology, t’hat t h e rostrum, ritbhirig on t h e under surface, was tlie plectra1 instrunlent of sound (Hoi~:i~pollo, Valeriano).

But these superficial notions conipetecl little with t h e Ai,istote- lixii liypotheses, which was repe:ttecl by inediEval :md la ter writers down t o hldrovandi (1618) and Moufet (1634), a n d constituted, from tlre snhola.stic viewpoint, a perfect explanation, requiring oiily abstention from renewed investigation to ensure its iiitlefiiiite perpetuation. The oiie glimmer of experimentnlism -the observstjion of Albertus Ilagiius (published 1405) t h a t cicadas could sing f o i n considemble period a f te r decapitatiun- servetl only t o confirin tlie theoi,y.

Tlie fiist, t o dispnte, in t’he opening of tlie seventeenth century, t h e a.ntliority “ die per. tant’ :mni n.vea c e h t o il vero,” were Cnsserius and Gnlileo. G:xlileo’s s ta tement is a clear expression of tlie nioderri spirit a.nd a clean sweep of tradition, b u t a t i t s pnblica.tion t,he effective organs of cicada. sound had been already cliscovered liy his contemporary. Gialio Casserio (Casserius), erstwhile tloinestic in the liouselioltl of Fa.hricius xb Ayuapendente and Ister liis successor in t h e Chair of Anatomy and Pliysics at Padna, piihlislietl i n 1600 a detailed illustrstecl acccunt of several species, figuring t h e t,ynIhals ( ~ m m d m t 7 i m bmcteales), mirrors ( $ I / ~ / L ~ C I ~ L ~ ) , folded rrienihrane ( n z e ~ i ~ b i ~ i n c e Zutem,), and tymhal- muscles, wliich l a t t e r he described as “ cid mouendas menzbmnas efecti.” The relatioris of t h e muscles a r e clearly sliomn, save t h a t tlie tei~niirinl disc and tendon :+re omit ted aiid tlre muscle drawn as insertetl directly on t h e tynilr):ai by a slightly narrowed apex. There is, however, some mistnke i n his experiment, since he reimrks concerning t h e folclerl nieinbiane (nzessibrcc7icc Zutea) ‘L tlisnipta smztcs perit.” Considering t h e t ime at which he wrote, a n d tlie more t1i:i.n a centmy’s interval which passed before his studies received R worthy suppIernentjt t h e contributioii of Casserius is highly nore~vorthy. H i s work, publishetl i n N. geiiera.1 ana.toinica1 t,reatise, seems largely t o ha^ been overloolied by his successors.

’l’he next account, t.ha.t of t h e Spaiiish botanist Giiilio Pontedera (1 718), f:i.lls considera.lily sliort of t h e standard set, by Casseiius so long hefore. It is t r c e t h a t h e proinises a fuller and illuati~ated description, bu t this apparently never appeai.ed. He indeed

.

MORPHOLOGY OF THE CICADIDA3- 469

recognized the tpmbals, and obssrved tha t the sound ceased when they were broken. His outlook was predominantly traditional, however, and he appeared stiil to believe that the tymbals were moved by the air enclosed in the body, but his accouiit is so obscur-e tha t one follows his thinking wlth difficulty.

Giovairibatista Felici is credited by Medici (1847. p. 142) with publishmg the first figures of the sound-organs (1724), but we have seen tha t another Italian, Cxsserio, lias no fewer than 124 years’ priority. Rnt if that honour go to Casserio, neveitheless the standard of Felici’s woik makes liiiii a worthy second.

Felici’s investigations were said to have been made and com- municated in 1717, seven years before publication. Felici held n generally correct view a5 to the relntione of all tlie parts ; he discovered the terminal plates of the tymbal-muscles, ossetti o cartilagimi dzcre, and the teiidons connecting them with the inner face of the tymbsl. H e knew no previous theories save those of antiquity, and these he criticised soundly, characterising the Aristotelian conception as a well-thought-out hypothesis-

‘( Ma quanto ( o Dio !). agevolmente s’ingannano coloro, che per investignre le cagioni degli effetti natuiali. non hanrio a h a rnigliore hcorta che la propria fantasia ! ”

By experiment he showed that the mirror and other necessary parts-one by one-could be eliminated as sound-prod ucers, until finally he could demonstrate this r61e in the t j nibals alone.

Felici figures and names five diffeieirt species of true cicatlas. Znnotti (1731) records the investigations of Pozzi (Putius) and

Laurenti, carried on some ten years previously. Those of Lxnrenti were devoted to the soulid-oigans. Zanotti refeis to Felici’s \voile, and i d s to show tha t Laurenti adds anything t o the latter’s contribution. The tynibals are desciibed, and the now almost usual experiment performed to show that their extirpation renders the arimal mute. The tymbnl-muscles are not , IioweT er, mentioned.

Swammerdani (1737, p. 504) knew no cicadas in nature : we niay therefore excuse his iepetition of the Aristotelian explanation.

Four times at lenst now lixd the true sountl-organs been independently discovered arid their niechanism moi e or less cleaily desciibed. It is significant that the pooiest account of the four was that of the investigator who placed the most emphasis on the teaching of the classics. To the extent that these isolated experimenters broke away from traditionalism, t o tha t extent also did they tend to ignore the work of their contemporaries and immetlinte predecessors. In no one were both tendencies more clearly displayed tlian in the fifth independent discoverer of cicada sound-organs. Bu t it was clue to the unfailing accuracy and patience of his observations, to the clarity and detail of his illustrations, and to the lucidity and charm of hi5 literary style tha t RCauniur (1740) not only escaped the oblivion which has

(1724, p. 67.)

470 DR. J. a. MYERS ON THE

largely swa.llowed the work of his forerunners, but supplied t h e sccoiiiit ~vhich is the basis of nearly all subsequent ciccumte clescript,ions of these organs. Even Fabre considered tha t the '' riiaster" had cleared up most of the mystery, leaving only a few suppleiiientary facts for his tlisciples to glean.

F'aLbre is right---tkiose who, like Landois (1867, 1874), loudly proclaim that., instead of aclcling a, little t o the work of their predecessors, they linve reaped an entirely new harvest, are found usually to have stored nothing but chaff. Re'aumur's account, reniar1i:able for i ts iincomproinising clenial of any other inotor agent than tha t f urnishetl by t h e tyiiibnl-muscles, is too well- kriown, :it least by imitation ant1 abridgment, to require further comment.

Later workers who, while adhering t o tlie essence of the Ileauiiiarian interpretntion, have in many cases adder1 greatly to our detailed knowledge of cicada. sound-organs are Carlet (1876 ( I ,

1876 h, 1877, 1879), who lias perhaps given the best generd account ; Fitbre ; H:(.swell (1 887) ; Lucas (1887) j Mayer (1 877) ; Lepori (1869); Goureau (1837, 1838); Targioiii (1865) ; Meilici (1847) : Lntreille (1822) ; Micldleniiss (1886); Hingston (1922); D u g i ~ (1838) ; Graber (1872, 1876, 1877) ; N. Potter (1839); Lloyd Morgan (1880, 1886).

Lepori and Goureau sliowed that the stigninta liad nothing to do witli tlie sound, since it was not altered when these were blocketl.

C:r.rns (1 829) einplia.sisec1 very strongly an dlegecl respiratory factor nieritionetl by C'hahrier (1820), but which Cariis clninied tha t R6auniur mid liis disciples hat1 overlooked. He obeet~ved (l'ibicen plebeia in Italy. Now plebeia is one of those species, like Meluiiqxalta scutellaris in New Zealnnd, which '' play " their instriiinents with considerable ingenuity, modifying the sound by alternately lifting the iLbdomen from and appressing it to t h e opercula, ~ n c l t h u s varying the size of the entrance to the sonncl- organ cavit#y. A t its gre;i.test divergence the abdomen is slightly curved tlorsail of the usua.1 outline of tlie budp, and appears swollen. The whole process looks very like a swelling a,nd deflating of the abdomen itself. Hingston (1922) describes i t as an nctual operation of this liintl-the abdoinen in a Hinia1:iyan species was seen to distend and collapse in accortlance with increase mid diminution of pitcli in the song. Yet a hole cut in the side of the abdomen a.nd of tile mesenteric sac failed to stop the song. Chrus, however, believes that, the movements were distinctly respiratory, and acconipanied tlie alternate expiration and inspiration of a i r through the third spiracles. H e regarded this process as per se essential t o sound-production, and knew nothing of the alternate increase and decrease of tlie space between operculn arid venter. I n this interpretation he was followed by Biirmeister (1833) ; van Hasselt (1882) Milde (1886) ; arid, in independent agreement, hy Soiier (1837). We

MORPlIOLOGY O F THE CICADIDE:. 47 1

have seen that Lepori, Goureau, and Hingston have supplied refuta1;iori based on experiment, while we have interpreted wi th Fabre, Swintoii (1880, p. 2 2 2 ) , a n d others t h e eEect, of t h e more- merits i n another way. Swiriton (especially 1908) would seem t o believe, nevertheless, t h a t t h e movements a re respii,atory.

There remain four theories which are now little inore t h a n historico-scientific curicsities. Griffini (1897) writes (p. 570) of cicadas :-

“ L e loro elitre hanno le nervaturn bxsali vesicolose, ossia alte

This alternate swelling and deflating of t h e “nt)i-vatura” produces cicada song !

Bartram (1 894) claims t h a t the males of Xagicicada septemkcirn niake a noise ‘‘ by a tremendous motion of two air-bladders under their wings.” H i s countryman Hildretli (1826), by a happy thought , extends th i s hypothesis t o expluiri also t h e origin of the Scottish national iiiusical instrument . H e refers t o septendecinz as “ screaming with their air-blarlders or bagpipes ” placed under their wings, a n d suspects t h a t t h e inventor of bagpipes received t h e idea “ from some insect of this kind ”-surely a Southron origin for t h e pipes. Possibly Hildreth was influenced by t h e question as t o tlie mnsica.1 properties of either instrument .

ltiisel(1749 I suffered with R e a u n ~ u r , whose work h e knew well, t h e tiisadvantage of working with (lead material. B u t while t h e French naturalist’s cicadas mere preserved i n alcohol, t h e Nukernberg observer liad apparently only dried specimens. He found tha.t t h e tendon from t h e terniirial plate of t h e tymbal- muscle was riot attached to t h e inner face of tlie tynibal, bu t actetl, he tlionglit, as a plectrum, eliciting sound by rubbing its t i p across t h e ridges of t h e Iattei,.

l!lie fourth schism from tlie now ovthoclox interpretation of R4:~uriiur was initiated Iiy Lanrlois (1867, 1872, 1874). Turn ing from his investigations on t h e buzzing of bees and flies, he attempted n siniilar explann.tion for cicadas- described complicated ‘ g Stinimbiinder,” bortlering t h e tllird spiracles, wliich he m i n e d “ Bchrillstignien ” a n d nnnourcrd as t h e sole instrument of sound. The tyrnbnl-muscles he waved airily aside-

“ Die Trommelmuslrel ist s ta rk chitinisirt und wurde von alteren Forschern einfxcli a ls Cliitinstibchen gecleutet. Die Muskelstructur desselben karin nach cler microscopiechen Untersuchung clurclians niclit zweifelliw~f t sein. Wegeii seiner stxrlien Chitinisirung kann dieses Tiibchen nicht contrahir t werden.” (1873, p. 348.)

H e calls Aristotle t o t h e support of his theory, a n d concludes t r i~i inpl i i~nt l y-

‘‘ So koniiiit man oft durch genaue mikroscopisclie Stndien wietler auf das zuriick, W A S die Viilker vor Jahrtausericlen richtig geahnt uncl benannt haben.”

:L tlilxtarsi ed a depriinersi alternntivariierite.”

(1867, p. 158.)

472 THE NORPEOLOCY O F TEE CICADIDB.

Landois's view, severely arid effectively criticised by his country- mail Qraher (1872), by Lloyd Morgan, and by Haswell, t o inention only :t few, was neveitheless accepted by Darwin (1871, p. 330), by Huxley (1878, p. 377\, and by a large number of text-books.

c. ACCESSORY STRIDULATIXG APPARATUS OF TETTIGADINB. Jacobi (1907 c) was the first to signalibe in t,he faniily

Oicaditire the existence of a. second sound-producing apparatus of a, far leas anomalous and complicated character than the one we have just studied.

The subfamily TettigaclinE, poor in genera and species, is essentially a neotropical group of fairly large, robubt forms, with extremely well-developed tyrnbals, richly ribbed. On the lateral angle of the mesonotuni is an inconspicuous oral area witliout hair, but with a series of strize running pardlel to the long axis of the body, and thus across the oval area, to which they are confined. In Tettigctdes chilensis A. 6 S., according to Jacobi, the ruts are not perpendicular to hlie surface, but inclined to forin short scales. We have been able to exa.n:ine only Choncsia crffissipemzis (Walk.), in which we have counted some 30 of these' ridges (text fig. 59). Jacobi states tliat there are between 15 and 35 in all species of T'ettigacles and ClzoTiosia studied, but only about 6 in B'abms.

\Vhile in other cicadas the hind-base of the clavus forms approxiniately a right angle (posterior tuherosity of Ama.ris), in Tettigades and CJ10~2osicc, according to Jacobi, i t is d r a w n out, while in Babras, it is extended inucli further into a rounded lobe. This is the plectra1 portion of the stridulatory n p p x t i i s . But no one has yet recorded observations in the field to est;t,blisli these a.ssumptioiis, and we confess tliat in 2honosia crnssi2ie7s7zis the anal lobe (text-fig. 55, pt . ) seems little more cleveloperl than in orctina.ry cicadas, though apparently capable, nerei~tlieless, of rubbing on tlie stridulatory surface (sa.).

This apparatus is equally developed in both sexes, and is espla,iiied by Jacobi as a & ' S~l i r ec l~mi t t e l~ ' a p i n s t such enemies as birds, the abdoiniiia.l sonnd-organs being devoted to sexual purposes. We should like field-observations.

I r i two of our largest New Zealand cicadas, Bfela~~zpsalta cingirlata and iW, sti*epita.izs, there is a loud wing-clicking protlncerl by botli sexes and additional t o tlie niale's song. It results from a rapitl h te ra l movement of the wings from the roof-like resting positiorl to one a t an acute angle with the body; but the movement is so quick tha t it is in~possible t80 be sure whether tlie noise is prodwed by friction between teginiiia anrl hind-wings on each side, or between one or both pairs and the body. I f the h t t e r , then the developlilent of the stridulating areas on the mesonotum of the Tettigadiria: is only a further step in tlie same direction.

Morphology of Cicadidae

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