221

This communication having extended far beyond the length that I at first coutcmplated, notwithstauding that I have limited myself in most cases to the distinctive peculiarities of the skuil, it will readily be seen that, had I entered upon the whole osteology of the order, or even introduced in every instance the characters by which the genus or species may be known externally, I should have swelled this little monograph to such a degFee as almost to preclude its insertion in the ' Proceedings' of the Society, and entailed upon myself an amount of labour from which I would by no means shrink, but fear I shall be compelled to defer until more favourable opportunities present them- selves; hut I trust that the little I have as yet accomplished may afford the natiiralist a clearer insight into the relations of the living Edentata among themselves, and with those that formerly peopled thc portion of the world which was then, as now, the principal abode of this remarkable group.

Pinilico, July 1851.

4. A MONOGRAPH OF SCUTUS, A GENUS OF GASTEROPODOUS MOLLUSCA, BELONGING TO THE FAMILY FISSURELLIDB.

BY ARTHUR ADAMS, R.N., F.L.S. ETC.

Genus SCUTUS, De Montfort. Animal with the head proboscidiform ; tentacles thick and subu-

late, with the eyes on tubercles at thcir outer bases ; mantle reflexed over the sides of, and nearly covering, the shell ; sides of foot with a series of short cirrhi.

Shell oblong, scutiform, flattened ; apex dorsal, oblique, posteriorly inclined ; margin of aperture sinuated in front ; muscular impression horse-shoe shaped, open anteriorly.

Yarmophorus, B1ainv.-Dascinus, Ra€in.-Xcutellites, Auct.- Xcutiim, Sow. jun.-Parmophora, Desh.-Emaryinula, sp. Sow.- Patella, sp. Laink.

1 . SCUTUS UNGUIS, Linn. Patel la unyuis, Linn. Mus. Ludovic. Ulric. Regin. p. 69. no. 419.

--Patella ambiyua, Chemn.-Scutus antipodis, Montf.-Parmo- phorus australis, Lamk.-Parm. elongatus, Blainv.

Hab. New Zealand. Mus. Cuming.

Patella elonyata, Lamk. Ann. du Mus. i. p. 310.-Parmophorus

IIab. East Australia. Mus. Cuming. Also occurs fossil.

3. SCUTUS GRANULATUS, Blainv. Parmophorus yranulatus, Blainv. Bullet. des Scienc. 181 7 ; Lamk.

Hist. An. s.Vert. vol. vii. pt. ii. p. 5 ; Reeve, Couch. Syst. pl. 139. f. 3 . Hab. Port Essington, on the rocks, low water.

2. SCUTUS ELONGATUS, Lamarck.

elongatus, Lamk. Hist.-Emarginzcla elonyata, Sow. Gen.

Mus. Cuming.

2 22

4. SCUTUS CORRUGATUS, Reeve. Parrnophorus corrugatus, Reeve, Proc. Zool. SOC. 1842 ; Conch.

Hub. -? Mus. Cuming.

5. SCUTUS TUMIDUS, Quoy et Gaimard. Parmophorus turnidus, Quop et Gaim. Voy. de l'Astro1. pl. 69. f. G.

-Parm. gibbosus, Anton.-? Parm. breviculus, Blainv. Bull. des Sci. 1817 ; Sowerby's Gen. (Emarg.) fig. 2.

Hub. Madagascar. Mus. Cuming.

G. SCUTUS IMBRICATUS, Quoy et Gaimard.

Syst. pl. 139. f. 1 .

Parinophorus imbricatus, Quoy ct Gaim. Voy. de l'Astrol. pl. 69.

Hab. Island of Burias. Mus. Cuniing. f. 17, 18.

7. SCUTUS ANGUSTATUS, A . Adam. S. testd elongatd, subqua- drangulari, luteribus angustatis, coarctatis; dorso plano, con- centrice striato, vertice subcentrali, postice declinato ; extremi- f a t e anticd sinuatd, posticd excurvatd, subelevatd.

H u b . Eastern Seas. Rlus. Cuming.

5 . A MONOGRAPH OF THE GENUS MONOPTYGMA OF LEA. BY ARTHUR ADAMS, R.N., F.L.S. ETC.

Genus MONOPTYGMA, J. Lea. (1 Menestho, Mull.) Animal unknown. Shell subulately turreted, transversely striated, apex simple, acute ;

aperture oval, longer than wide, rounded and entire in front ; colu- mella with a single oblique fold.

This genus differs from Actaox in being elongated, and in having an oblique fold, instead of a transverse plait on the columella.

1 . MONOPTKGMA STRIATA, Gray. M. testd turrito-subulutd, so- lidd, olivaceif, uizfractibus plunk, transversim sulcatis, subcis profundis, distaiitibus ; aperturd oblongd, intus albd.

This species, which is typical, is a very thick and strong shell, with a somewhat convex lateral outline, and strongly transversely grooved across the flattened whorls. Mus. Cuming.

2. MONOPTYGMA FULVA, A. Adams. M. testd turrito-subulatd, graciliori, solidd, fulvd, anfractibus planis, fransaersim sulcatis, sulcis profundis, distantibus ; aperturd oblongd, intus fused.

This elegantly-formed shell is more slender than M. striata, and of a different colour; the transverse grooves are also much closer together, and their edges are rounded ; the twist of the columella is not so distinct, and the aperture is brown internally. Mus. Cuming.

M . fcstd ovato-tur- ritd, nfbd, solid$, anfrcictibus plattiitscit f is, gradatis, longif i d ' -

3. MONOPTYGMA GRANULATA, A. Adams.