ON THK MALLEUS OP THE LACERTILIA, ETC. 579

On the Malleus of the Lacertilia, and the Malarand Quadrate Bones of Mammalia.

By

M. 1>. I>ollo,

Assistant-Naturalist in the Royal Museum of Natural History, Brussels.

With Plate XLI.

THK apparent absence of a quadrate bone in Mammals hasgiven rise to a large number of theories, differing in details, butall, or nearly all, tending to discover this bone in the chain ofossicula auditus of these animals. A recent work, publishedby my friend Professor P. Albrecht,1 departs, however, fromthe view ordinarily taken, and, as I believe, advances ourknowledge considerably on the subject. I have been led bythe study of this memoir to a discovery which I believe to beof considerable interest, of which it is the object of the presentcommunication to give an account.

Before passing to the consideration of my own observationsI will briefly review the state of the question. This cannot bebetter accomplished than by reproducing the excellent recapi-tulative tables given by M. Albrecht.

1 P. Albrecht, " Sur la valeur morphologique de l'articulation mandibulaire,du cartilage de Meckel et des Osselets de l'oirie, avec essai de prouver quel'ecaille du temporal des Mammifers est composee primitivement d'un squa-mosRl et d'un quadratum " (Mayolez, Bruxelles, 1883).

580 M. L. DOLLO.

TABLE I.1

Theories published up to the present time on the Morphological

Differences between the Mandibular Articulatiou of the

Lower Gnathostomous2 Vertebrata and the Mammalia.

Maiidibular Articulatiuii of Oie LowerGnathostomous Vertcbi'ata.

Quadrato-articular articula- }tion I

Mandibular Articulation of Mammalia.

Huxley' . .

Gegenbaur4 .v. Kolliker6 .

f Squamoso-mandibular nrti-X culation.

Dentary articulation.Ditto, ditto.

1 P. Albrecht, op. cit., p. 249.2 E. Haekel, 'Anthropogenie/ Leipzig, 1874, p. 425.3 Huxley, ' A Manual of the Anatomy of Vertebrate Animals,' London,

1871, p. 84. Wiedersheim, 'Lehrbuch der vergleiclienden Anatomie derWirbelthiere,' Jena, 1882, T. i, p. 139 and 155.

4 Gegenbaur, ' Grundziige der vergleichenden Anatomic,' 2' Auflage, Leip-zig, 1870, p. 663.

5 V. Kolliker, ' Entwicklungsgeschichte des Menschen iind der hoherenThiere,' 2' Auflage, 1879, p. 486.

THE MALLEUS OF THE LAOERTIL1A, ETC. 581

TABLE I I . 1

Theories on the Development and the Morphology of theOssicula Auditus of Mammalia.

Manaibular Arcli. Hyoidean Arcb. AuditoryCapsule.

Reichert* .Giinther*. ,

Gegenbaur4 . <

Huxley5 . ,W. K. Parker6.W. K.Parker 1and Bettany7 3

Salensky8 . ,

V. Kolliker9. j

Wiedersheim10

Malleus, Incus . . .Malleus, Incua, StapesMalleus (Articular). \Iucus (Quadrate) . )

Malleus (Quadrate) jDittoDitto

Stapes.

Os lenticulare (Symplectic).

Stapes (Hyomandibular)Incus (Hyomandibular)Os lenticulare, Stapes.Ditto.Incus (Hyomandibular) jStapes.

Malleus, Incus, StapesMalleus (Articular). ,Processus gracilis (An-

gular) . . .Incus (Quadrate)Ditto

, . |Stapes.

. . Ditto.

1 P. Albrecht, loc. cit., p. 250.1 Reichert, " Ueber die Visceralbogen der Wirbeltbiere," ' Miiller's

Archiv,1 1837.' Giinther, ' Beobachtungen \iber die Entwicklung des Gebororgans,1 Leip-

zig, 1842.* Gegenbaur, loc. cit., pp. 662 and 663.* Huxley, loc. cit., and ' Proc. Zool. Soc. London,' 1869.6 P. Albrecht, loo. cit., p. 250.* Parker and Bettany, 'The Morphology of the Skull/ London, 1877.8 Salensky, "Zur Entwicklungsgeschichte," 'Zoologischer Anzeiger,'Leipzig,

Jahrgang ii, p. 250.0 V. Kolliker, loc. cit., pp. 471—473, 475—478, 480—487.10 Wiedersheim, loo. cit. See also Salensky, ' Morpholog. Jahrbuch,' vol.

vi, p. 415 ; and Eraser, ' Philos. Transact.,' 1883, p. 901.

VOL. XXIII. NEW SEH.

582 M. L. DOLLO.

TABLE III.1

Theories on the Morphological value of the Incudo-tnallear and

the Mandibular Articulations of Gnathostomous Vertebrates.

Gegent) | Huxley, ParkQT and Bettany.

Incudo-mallear of Mam-1 Quadrato-articular.malia. <

Mandibular of Lower Quadrato-articularGnathostomous Verte-brata.

Mandibular of Mammalia.

(viz. Incudo-mallear).

Squamo'so-dentary.

Hyomandibular- ;quadratic.

Quadrato-articular(viz. Malleo andArticular).

Squamoso-articular.

From the contents of these, tables it follows :1st. That according to the anatomists who have preceded

M. Albrechtj the lower gnathostomous Vertebrata have theirjaws hinged by means of a quadrato-articular articulationjwhilst Mammalia are provided with an entirely different kindof articulation, concerning the exact nature of which theseanatomists are at variance.

2nd. That according to the same authors the Promammalia2

must have possessed originally a quadrato-articular articulationof the lower jaw, but that they have lost it (Huxley, Parker ,and Bettany), or at least have given up its use in the actof mastication (Gegenbaur and von Kolliker) , and that at thesame time their quadrate (Huxley, Parker , and Bettany), andperhaps also the articular (Gegenbaur and von Kolliker) andangular elements (von Kolliker) of their mandible have becomeincluded in the chain of the ossicula auditus.

After this statement M. Albrecht3 continues :1st. Tha t he is persuaded that all of the ossicula auditus

of Mammalia are represented by ho.mologues in the Amphibia,and by all the ossicula auditus of the Sauropsida, and thatthey correspond to the suspensorium of fish. The facts maybe stated as follows :

1 P. Albrecht, loc. cit., p. 12.2 B. Haeckel, ' Natiiriiclie Sckopfungsgescliiclite,' Berlin, 1872, p. 538.3 P. Albrecht, loc. cit., p. 251.

THE MALLEUS OF THE LACERTILIA, ETC. 583

Mammalia.

Sauropsida.

I (Urodela.s. ( Auoura.

Fenestra tym.panics.

Aibrecht.

Membranatympauica.

Ditto.

Ditto.Ditto.

Interfenestral Chain, Aibrecht, extend-ing, without interruption, from one Feuestrato another

Malleus 4- Incus + Os lenticulai-o•+• Stapes.

Columella auris.

Ditto.1st ossicle + 2nd ossicle + 3rd ossicle

+ 4th ossicle.

FeneBtra

Membranaovalis.

Ditto.

Ditto.Ditto.

Further :

Mammalia.Sauropsida.Amphibia.Pisces

Mandible.Ditto.Ditto.Ditto.

Extramandibular portion of Mec-kel's Cartilage and InierfenestralChain.

Suspeusorium.

Otic Regionof Cranium.Ditto.Ditto.

Sj since the quadrate does not form any part at all of theinterfenestral chain of Sauropsida, it cannot enter into thecomposition of that of Mammalia.

2nd. That it is not possible to understand (especially on thetheory of Gegenbaur, v. Kolliker, and others) how the Mam-malia could have acquired an articulation of the lower jawdifferent from that of other gnathostomous Vertebrata, and that,therefore, he is of opinion that the glenoid cavity of Mammaliaought still to be found in the quadrate bone.

M. Aibrecht has in his hands at the present time the skullof a new-born child, in which the squamous portion of thetemporal bone is divided into two parts, viz.:

a. The squamous portion of the temporal bone, properly socalled, the homologue, in his opinion, of the squamosal ofSauropsida.

/3. The zygomatic portion bearing the glenoid cavity, andthus homologous, with the quadratum of the Sauropsida.

Other cases of the complete separation of the squamosal andthe quadrate are mentioned in literature, and are cited by M.Aibrecht. In addition this distinguished anatomist states thathe has observed traces of a squamoso-quadratic suture in several

584 M. L. DOLLO.

skulls of apes in the Royal Belgian Museum of Natural History,and that he will shortly publish an account of them.

To sum up, M. Albrecht's arguments lead, on the whole, tothe following two conclusions :

1st. The quadrate cannot form part of the interfenestralchain of bones of Mammalia.

2nd. One of the two bones (the zygomatic portion) formedby the division of the so-called squamosal is doubtless thehomologue of the quadrate of Sauropsida.

I shall examine these two statements successively, in orderto show whether the results of my own observations tend toconfirm or invalidate M. Albrecht's conclusions.

I.

Can the quadrate form a part of the interfenestral chain?It is evident that if there were found simultaneously existing

in the same animal a mandible composed of six normal elements,a true quadrate, and a malleus, it would immediately followthat it was impossible that that quadrate could form any partof the chain of ossicula auditus, for—

1st. It could not be confounded with the malleus, becausethere would already be one there.

2nd. It would be still more impossible to identify it withthe remainder of the interfenestral chain, because it would besituated outside the malleus, and would not touch any of theremaining ossicula.

Everything depends, therefore, on the discovery of a malleusin the condition described above. Now, I have found in severalLacertilia (Leiolepis gu t t a tu s , Ctenosaura pec t ina ta ,Uromast ix sp in ipes , Lophyrus di lophus, Basi l iscusvi t ta tus) a small bone which appears to answer the question.I shall endeavour to prove that it has really the morphologicalvalue of a malleus.

a. Firstly, it has the form of a malleus; it being possible todistinguish in i t :

THE MALLEUS OF THE LACERTILTA, ETC. 585

a. A capitulum.b. A cervix.c. A manubrium.d. A processus gracilis.

(3. It has the same connections; that is to say:a. It is applied along the tympanic membrane in such

a manner that the manubrium is parallel to the mem-brane.

b. It is united besides to the remainder of the inter-fenestral chain by means of a cartilage attached to it inthe region of the cervix.

c. It lies in contact with the quadrate in exactly thesame manner as that in which the malleus of Mammaliais in contact with the quadrate of M. Albrecht.

y. It is connected with the articular element of the man-dible bymeans of a malleo-articular ligament, which M. Albrechtidentifies with the extra-mandibular portion of Meckel's carti-lage.

8. There is little doubt, there appears to me, that this mal-leus is identical with that described by Peters as existing inthe crocodile,1 and with the " suprastapedial extrastapedial(manubrium) " of Mr. W. K. Parker.2

This being admitted, the first of the naturalists cited hasdemonstrated the continuity of the malleus with Meckel'scartilage, as in Mammalia,3 an observation confirmed by theEnglish naturalist. This result, therefore, is in support ofthe opinion expressed in S.

e. The malleus of Mammals serves for the insertion of asmall muscle (tensor tympani), the origin of which is in the oticregion of the cranium. The same occurs in the case of themalleus of Lacertilians.4

1 W. Peters, ' Monatsberichte d. K. p. Akademie d. Wissenschaften zuBerlin,' 1868, p. 592.

2 "W. K. Parker, 'Phil, Trans. Roy. Soc.,' London, part, ii, 1879, pi. 43,fig. iii and vi.

3 W. K. Parker, ' Nature,' July 13th, 1881, p. 253.4 W. K. Parker, 'Phil. Trans.1 (v. supra), fig. vi, st. m. (the so-called

" stapedius " of the author).

586 M. L. DOLLO.

To sum up, then, I believe that I have discovered in Lacer-tilia a real malleus, the homologue of that of Mammalia, andwith that fact as a starting-point it appears that the conclu-sion may he formed that the quadrate of Mammalia is not toto be sought for amongst their ossicula auditus. In thisrespect, therefore, M. Albrecht's theory receives confirmation,although it will be necessary that it should be slightly modi-fied. Instead of the statement with regard to reptiles r1

Columella = malleus + incus -f- os lenticulare + stapes, thematter must stand thus :

Columella = incus 4- os lenticulare + stapes.

II.

Is the quadrate of M. Albrecht really the homologue of thequadrate of Sauropsida ?

Such is the second question to be considered. Before goingfurther it will be well to consider what are reasons given byM. Albrecht in favour of his interpretation. They are threein number.

1st. The quadrate of Mammalia, since it could not findplace in their interfenestral chain, must be to be found else-where.

2nd. The glenoid cavity ought still be found in the quadratebone.

3rd. There are a certain number of instances known inwhich the squamous portion of the temporal bone of man, orof the primates, is divided into two parts.

a. The squamous bone properly so called.J3. The zygomatic portion.

It appears to me that two further methods of inquiry shouldbe employed to make certain whether the quadrate of M.Albrecht is a real quadrate or not. These are :

1st. The examination of its connections.2nd. The study of its development.

1 P. Albrecht, loc. eit., p. 15.-

THE MALLEUS OF THE LAOBRTILIA, ETC. 587

Leaving aside the latter question, to which M. Albrecht pro-poses to return shortly, the attempt will be made to demon-strate the correctness of his views by the former method.

Nevertheless, before this interesting subject is commenced,it is indispensable to determine the morphological value of themalar bone of Mammalia, since this determination will be ofthe greatest utility in the sequel.

In a recent work1 M. Albrecht, has proved that the malarbone of Mammalia ought to be considered as formed of threeparts, which he calls

1st. A premalar. ~|2nd. A postmalar. . I See the Figs. 1, 2, 3, 4, below.3rd. A hypomalar. J

FIG. 1.—Diagram of the malar bone divided into two parts by a horizontalsuture. (The Japanese bone.) (After P. Albreclit).

x + y. Post-malar (Posterior postfrontal, Albreclit.) (Post-frontal, Dollo). + Premalar (Anterior postfrontal, Albrecht.)(Jugal, Dollo). z. Hypomalar. (Quadrato-jugal, Albrecht).

1 P. Albreeht, " Sur le Crane d'une Idiote de 21 ans," ' Bull. Soc. Anthro-pologie d. Bruxelles,' T. I., p. 163.

588 M. L. DOLLO.

PIG. 2.—Diagram of the malar bone divided into two parts by a verticalsuture. (The right malar bone of the cranium of Albrecht's idiot.)(After P. Albrecht.,)

y. Premalar (Anterior postfrontal, Albrecht.) (Jugal, Dollo).x + z. Postmalar (Posterior postfrontal, Albrecht). (Post-frontal, Dollo.) 4- Hypomalar (Quadrato-jugal, Albrecht).

FIG. 8.—Diagram' of the malar bone divided into three parts, constructed fromthe bipartite malar with the horizontal suture (the Japanese bone), andthe bipartite malar with the vertical suture (right malar of Albrecht'sidiot). After P. Albrecht.

x. Postmalar (Posterior postfrontal, Albrecht) (Postfrontal,Dollo). y. Premalar (Anterior postfrontal, Albrecht.) (Jugal,Dollo.) *. Hypomalar (Quadrato-jugal, Albrecht).

THE MALLEUS OF THE LACEBTILIA, ETC. 589

Fio. 4.—Diagram of the normal malar. (After P. Albrecht).* + y + z. Postmalar (Posterior postfrontal, Albrecht.) (Post-

frontal, Dollo). + Premalar (Anterior postfrontal, Albrecht.)(Jugal, Dollo). + Hypomalar (Quadrato-jugal, Albrecht).

By comparison with the Sauropsida M. Albrecht arrives atthe following interpretation of these parts :

Premalar—Anterior postfrontal.Postmalar—Posterior postfrontal.Hypomalar—Quadrato jugal.

Lastly, in his opinion a small isolated bone discovered in ayoung Cynocephalus appears to represent the jugal, whichis usually co-ossified with the supramaxillary bone.

I regret that I cannot agree with his conclusions, for in fact:1st. The bone of the Cynocephalus appears to me to be

simply a wormian bone, which has appeared at this spot as iffor the very purpose of leading to the construction of a theory.

2nd. In M. Albrecht's comparison, the jugal is excludedfrom taking part in the contour of the orbit, an arrangementof which I know no other example, not even in the Lacer-tilians with the double postfrontal.

3rd. Why should it be desired to assign to the human sub-ject two postfrontals, when in the Sauropsida this structure isonly to be met with amongst the Lacertilia, and even amongstthese an exception rather than the rule ?

(Continued on page 592.)

SUPR

A-T

EM

POR

AL

A

ND

LA

TE

RO

-TE

MPO

RA

L

FOSS;E

O

F E

XIST

ING

SA

UR

OPSID

A

AN

D M

AM

MA

LIA

.

A Q

uadrato-JugalN

o Quadrato-Jugal and therefore no latero-tem

poral fossa-

A squam

oso-postfrontal arch, and

therefore separate supra- and la-tero-tem

poral fossa;.

I.B

oth closed.II.

Both open.

No squam

oso-postfrontal arch, supra- and

latero-temporal fossse confluent, giving

rise to a supra-latero-temporal fossa.

Squamoaal united to

Squamosal not united

the Quadrate and

to the Q

uadrato-Q

uadrato-jugal. jugal.

IX.

A

squamoso - postfrontal

arch, separating off asupra-tem

poral fossa.

Pstfr

Sq Pstfr

Postfrontal unitedto the Q

uadrateand Q

uadrato-1. L

acertilia,?except H

atteria andthe exceptions in X

.

\/

J - Q

j - Q

J -

Qj

1. Chelonia.

1. Khynchoce-phalia. 1

2. Crocodilia.

X.

No squam

oso-postfrontalarch, and therefore nosupra-tem

poral fossa.

PstfrSq

1. Ophidia. 8

2. Aniphisbcena. 9

3. Ascalabota. 10

4. Ch

alcidea."

"I5. S

cinco

idea." J

6. Chelys. 13

Patfr

1. Teatud

1. Mam

malia, 5

J — Q

j — Q

except in N

o. VI.

1. Lophiom

ys. 4

THE MALLEUS OP THE LAOERTILU, ETC 591

(Notes to the tabular statement on page 590.)I observe the followiag arrangement in R-hynchosuchus Schlegelii :

Pstfr

Rhynchosuchus Schlegelii.

This fact will be made use of in a moment.2 Cuvier, ' Ossemens fosailes,' 1836, pi. 239, figs. 9—12.3 Cuvier, loc. cit., figs. 17—20.4 A.- Milne-Edwards, "Me'moire sur le type d'une nouvelle famille de

1'ordre des Ronguers," ' Nouvelles Archives du Museum de Paris,' 1867,p. 66 and pi. vii, figs. 1, 2, 3, 4.

* The formula, as well as the preceding one, assumes that the quadrateof M. Albrecht is really a quadrate. Otherwise we have:

Pstfr

Mammalia.

that is to say, the structure of a Chelonian, in which the supra-temporal fossahas remained open, and in which the quadrate has been withdrawn and trans,formed into an auditory ossicle.

• T. H. Huxley, ' A Manual, &c.,' p. 282.i T. H. Huxley, 'A Manual, &c,' p. 220.s T. H. Huxley, 'A Manual, &c.,' p. 233—238.9 T. H. Huxley, ' A Manual, &c.,' p. 230.10 T. H. Huxley, ' A Manual, &c.,' p. 225." T. H. Huxley, 'A Manual, &c.,' p. 22S.ia T. H. Huxley, ' A Manual, &e.,' p. 228.13 Cuvier, loc. cit., Qgs. 21—34.

592 M. L. DOLLO.

4th. M. Albrecht's ' former interpretation, viz. that the jugalwhen it is not ossified by a particular centre is ossified eitherby the supra-maxillary or by the quadrato-jugal, appears to meeven less capable of defence, for among the living Sauropsidapossessing a quadrato-jugal Ha t t e r i a i s the only one in whichthis bone is fused to the jugal. In Hatteria we have to dealwith an exception. Therefore, why should it be desired torender the condition in the human subject a matter of excep-tion rather than to bring it within the rule ? In other words,it appears to me more rational to assign to Man a separatequadrato-jugal, such as occurs in Birds, Chelonians, andCrocodilia.

The explanation which follows seems to me a more correctone, because by its application all the objections we have justpassed in review disappear.

Premalar = Jugal.Postmalar=Postfrontal.Hy pom alar=Quadrato-j ugal.

This, if M. Albrecht's quadrate be admitted, gives us theformula:

Pstfr

Homo.

Let us attempt to discover in the Sauropsida an analogousarrangement, in order to better justify our theory.

If a skull of H a t t e r i a be examined, it is seen that threetemporal fossa? can be distinguished,3 a latero-temporal, asupra-temporal, and a post-temporal. I have discussed thevariations of the latter at length in another memoir,3 and it

1 P. Albrecht, ' Sur la valeur tnorphologique de l'articulation mandibulaire,&c.' Hypomalar = Jugal + Quadrato-jugal.

s T. H. Huxley, 'A Manual, &c.,' p. 220.3 L. Dollo, " Quatrieme note sur les Dinosauriens de Bernissart," ' Bull.

Mus. Roy. Hist. Nat. Belg.,' t. ii, p. 242.

MALLEUS Ol1 THE LACERTILIA, ETC. 593

is not therefore necessary to return to the subject here. Letus study the variations of the two former; they are compre-hended in the table on page 590.

Let us now compare the formula given for man with that ofRhynchosuchus Schlegel i i .

Pstfr Sq Patti-

Homo sapiens. Rhynchosuclius Schlegelii.

Only two things are necessary to pass from one to theother, viz.:

1st. The disjunction of the squamoso-postfrontal arch.2nd. The closing together of all the other bones under con-

sideration.Now, the former condition is very common amongst the

Sauropsida. It is to be observed, as has been already stated,in the Ophidians, the Amphisboenidse, the Ascalobotidse, theChalcidea and Ophidiiform Scincoidea, the Chelonia, and inBirds.; whilst the latter is by no means rare amongst theChelonia.

In short, my explanation of the malar bone of Mammaliaavoids entirely the objections raised by M. Albrecht's theory,and exhibits a simple combination of the known phenomenain Lizards:

Malar = postfroutal + jugal + quadrato-jugal.Before resuming the discussion concerning the quadrate, I

may again express my opinion, based on the facts which follow,that—

1st. The Lacertilia and Ophidia possessed originally anossified quadrato-jugal.

2nd. That therefore there existed originally in all the Sau-ropsida a latero-temporal fossa bounded thus:

594 M. L. DOLLO.

Pstfr Sq

Sauropsida.

My reasons are as follows :1st. The ancient Reptiles (Ichthyosauria, Plesiosauria, Dino-

sauria, &c.) possessed an ossified quadrato-jugal2nd Amongst the existing Sauropsida, Birds, Crocodiles,

and Chelonians, as well as Hatteria, possess one still.3rd. This latter animal represents amongst the Lacertilia a

primitive type, as it is closely allied to the Triassic Rhyncho-saurus.

4th. The quadrato-jugal exists still in a ligamentous con-dition in the Ophidia and Lacertilia, and this is certainly anindication of rudimentation since in all the Chalcidese and ophi-diiform Scincoidea the squamoso-postfrontal arch likewisebecomes ligamentous

Let us now consider by what peculiarities in its connectionsthe quadrate of Sauropsida is distinguished, and then examinewhether these peculiarities are also to be found in M. Albrecht'squadrate.

The quadrate of Sauropsida may be iu relation—1st. At its proximal extremity with the squamosal, the pa-

rietal, and the parotic process (Iguana).2nd. At its proximal extremity again with the malleus

(Uromastix).3rd. At its distal extremity with the mandible and the

pterygoids (Iguana).4th. At its distal extremity again with the quadrato-jugal

(Crocodile).5th. Occasionally with the postfrontal (Rhynchosuchus).6th. Lastly, with the tympanic membrane, which is inserted

into it in a posteriorly placed concavity, which might be termedthe tympanic concavity (Iguana).

THE MALLEUS OF THE LAOERTILIA, ETC. 595

Now, all these relations, excepting the one with the ptery-goid, occur in the case of M. Albrecht's quadrate. If, then,it is borne in mind that it is solely because of the enormousdevelopment (compared to that in the Sauropsida) of the alis-phenoid in man that the separation of the quadrate and pterygoidis due, it will be admitted that M. Albrecht had good groundsfor holding the quadrate of the lower gnathostomous Verte-brata as homologous with the zygomatic portion of the squa-mous part of the temporal bone of Mammalia.

SUMMARY.To resume :I. I believe that I have discovered in Lacertilia a true mal-

leus homologous with that of Mammalia, and that this circum-stance allows of a modification of the table of homologies givenby M. Albrechtx in the following manner.

Interfenestral Chain.

Fishes iu general Suspensorium. .Teleosteans Symplectic... + Hyomandibular. ISauropsida ! M. tyaip. ... Malleus + Columella M.ovalis.IMammalia | M. tymp. ... Malleus + Incus + Os |

lenticulare + Stapes ...M. ovalis. IM. tymp. ... Columella M. ovalis. ',M. tymp. ... lstossicle + 2nd ossicle

+ 3rd ossicle + 4thossicle + M. ovalis. i

II. I believe that I have determined the morphologicalvalue of the malar bone of Mammalia. It is as follows:

Malar = postfrontal + jugal + quadrato-jugal.1 P. Albrecht, ' Sur la valeur morphologique, &c.,' p. 253, m.Albrecht has also communicated to me his idea that the Mallens is nothing

else than the symplectic of Teleosteans. The grounds on which he supportsthis opinion are, that according to Stannius the extra-mandibular portion ofMeckel's cartilage fixes itself upon the symplectic. I am the more disposed toadmit the correctness of this homology because, in the Lacertilia, it is to beclearly observed that the Malleus (in regard to which M. Albrecht agrees withme) is the intermediate bone between the quadrate aud the columella (hyoman-dibular), just as in the osseous fishes the symplectic is interposed betweenthe quadrate and the hyomandibular.

596 M. L. DOLLO.

This may be expressed in the following formula :

Pstfr

Homo.

relations which are to found amongst the Sauropsida also.III. Lastly, I have by the study of the connections of the

bones materially strengthened M. Albrecht's theory, whichholds that the zygomatic portion of the squamous part of thethe temporal bone of Mammalia is the homologue of the quad-rate of the lower gnathostomous Vertebrata.

In conclusion, it is my duty, which is very agreable to me,to thank my learned friend, Professor P. Albrecht, for theliberality with which he has placed at my disposal the woodblocks which he has used in the illustration of his two recentmemoirs, and all the more so because they are to be used toattack one of the theories of the distinguished anatomisthimself.