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Show 322 MOLLUSCA. by one whorl and a half, umbilicated on one side, and flattened on the other. The animal uses its shell as a boat and its wings as oars, whenever it wishes to navigate the surface of the deep. Clio helicina, Phips and Gmel.; .llrgonauta arctica, Fab., Faun. Groenl., 387. Almost as common on the arctic seas as the Clio borealis, and is considered as forming the chief source of food for the Whale(l). HYALEA, Lam.,-CAVOLINA, Abildg. Two large wings; no tentacula; a mantle cleft on the sides, lodging the branchire in the bottom of its fissures, and invested by a shell also cleft 1 aterally, the ventral face of which is arched, and the dorsal flat and longer than the other; the transverse line which unites them behind, furnished with three sharp dentations. When alive, the animal thrusts several appendages, that are more or less long, through the lateral fissures of its shell; they are productions of the mantle. H. cornea, Lam.; JJ.nomia tridentata, Forskahl.; Cavolina na· tans, Abildgaard; Cuv ., Ann. du Mus., IV, pl. 59; and Peron, lb., XV, pl. 3, f. 3. A srpall, yellowish, semi-diaphanous shell, found in the Mediterranean and the Atlantic Ocean(2). CLEODORA, Peron. The Cleodorre, for which Brown originally created the genus Clio, appear to resemble the Hyalere in the simplicity of their wings and in the absence of tentacula between them; it is also probable that their branchire are concealed in the mantle; their conical or pyra· midal shell, however, is not cleft on the sides. M. Ray distin· guishes CLEODORA, properly so called, with a pyramidal shell, CRESEIS, with a conical and elongated shel1(3), (1) I am not sure that the animal drawn by Scoresby, of which de Blainviile (Malac., pl. xlviii, bis, f. 5) makes his genus SPIRATELLA, is, as he thinks, the same as those of Phips and Fabricius. (2) Add: Hyal. lanceclata, Lesueur, Bullet., des Sc. June 1813, pl. v, f, 3;Hyal. in.ftexa, lb., f. 4. N.D. The Glaucus, Carinaire, and Firole, referred by Peron to the family of the PnnoPODA, belong to the GAsTEROPOnA; the Philliroe of the same author also probably belongs to it.-His Calliani're is a Zoophyte. ( 3) It is probably near the Creseis, and perhaps even in the same subgenus, according to Messrs Rang and Audouin, that we must place the genus TaiPTJ:ll! of Messrs Q.uoy and Gaymard, which iR referred by M. de IUainville to the family of the Akera:. PTEROPODA. CuviERA, with a cylindrical shell, PsYCHE, with a globular shell, and EuRYBIA, with a hemispherical shell( 1 ). PYRGO. 323 It is thou~ht that ':e may approximate to the Hyalere, this very small fossil shell discovered by M. Defrance. It is vet·y thin, globular, and divided by a very narrow transverse cleft, except before where it becomes somewhat widened. ' (1) See the M6m., of M. Rang, Ann. des Sc. Nat., Novcmb., 1827, and March 1828. N.B. Several Pteropoda have been discovered in a fossil state. M. Rang has found, near llourdeaux, 1/yalem, Cwvierim, and Cleodorte. See Ann. des Sc. Nat. August 1826. The Vaginella of Daudin is a Cresis according toM. Rang; it has~ in fact, all the characters of the latter. \ |