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Show 396 MOLLUSCA. LIMA, Drug. The Lim::e differ from the Pectens in the superiot• length of their shell in a dit·ection perpendicular to the hinge, the ears of which are shorter, and the sides less unequal, thus forming an oblique oval. The ribs of most of them are relieved with scales. The valves cannot join during the life of the animal, whose mantle is furnished with numberless filaments of different lengths without tubercles, and more internally, with a large border which closes the opening of the shell, and even forms a veil in front. The foot is small and the byssus trifling. The Lim::e swim with rapidity by means of their valves. One species, the Ostrea lima, L.; Chemn., VII, lxviii, 651, of a fine white, inhabits the Mediterranean. It is eaten(!). PEDUM, Brug. The oblong and oblique shell with small ears, of the Limre; but the valves are unequal, and the one only that is most convex has a deep emargination for the byssus. The animal is similar to that of a Lima, but its mantle is only furnished with a single range of small, slender tentacula. Its byssus is larger. But a single species is known; it inhabits the Indian Ocean(2). Certain fossils may be placed here which have the hinge, ligament, and central muscle of the Ostrere, Pectines, and Limre, but are distinguished by some of the details of the shell. HINNIT A, Defr. The Hinnit::e appear to be Ostre::e or Lim::e with small ears, and adhering, irregular and very thick shells, the convex valve in parti· cular. A depression is observed on the hinge for the ligament(3). (1) Add: Ostrea glacialis, Chemn., VII, lxviii, 652, o53;-0str. excavata, lb., 654;-0str. fragilis, lb., 650;-0str. hians, Gualt., LXXXVIII, FF, G. For the fossil species see Lamarck, Ann. du Mus., VIII, p. 461; Brocchi, Conch. Foss., and Sowerb., Min. Conch. (2) 01t1·ea spondyloi·dea, Gm., Chcmn., VIII, lxxxii, 669, 670. (3) Some living species have very lately been l'eferred to the genus HxN:!UT!, Defr. M. Gray,-Ann. of Phil., August 1826,-describes one by the name of Bin· nita gigantea; Sowerby,-Zool. Journ. IX, p. 67, adds a second by that of Jl, corallina; fiJ)ally, l\1. Deshaies refers the Ostrea sinuosa, L, to this genus, and de· ACEPHALA TEST ACE A.. 397 PLAGIOSTOMA, Sowerb. The oblique shell of a Lima, flattened on one side; very small ears; the valves more convex, striated, without scales, the opening for the byssus smaller(!). Found in formations anterior to chalk. P ACHYTEs, Defr. Nearly the same form as that of the Pectines; shell regular, with small ears; a flattened transverse space between their summits, which in one of the valves is marked by a deep triangular notch, in which passed the ligament. Found in chalk(2). In the DIANCHORA, Sowerb., The nlues are oblique and irregular, one of them adherent and with a perforated summit, the other free and with ears(3). PoDoPsts, Lam. Regular striated valves without opercula; the summit of one of them more salient, truncated and adherent, frequently very thick, and forming a sort of pedestal to the shell( 4 ). Although multivalve, we should approximate the •' ANoMIA, Brug. To the Ostre::e. The Anomi::e have two thin, unequal, irregular valves, the flattest of which is deeply notched on the side of the ligament, which is similar to that of the Ostre::e. The greater part of the central muscle traverses this opening t? be inserted into a scribes a fourth living species under the name of Hinnita Defrancii; M. Defrance also admits two fossil species, the H. Cortesii, Blainv., Malac., pl. lxi, f. 1, and the H. Dubuissonii. (1) Plagiostoma gigas, Sowcrb., Encyc. Method., Test., pl. 238, f. 3;-Pl. Ire· vigatum, Parkins., Org. Rem., III, pl. xiii, f. 6; and the other species given by Sowerby, Min. Conch., pl. 113, 114, and 382. (2) Pachytos spinosus, Fr. Soweru., Cuv., Oss. Foss., II, Env. de Paris, pl. iv, 2, A, H, C, and Blainv., Malac., pl.lv, f. 2:-Pach. hoperi, Sowerb., 380. (3) Dianch. striata;-D. lata, Sowerb., Min. Conch., pl. 80. (4) Podops. truncata, Encyc. pl. 188, f. 2, 6, 7; Cuv., Oss. Foss.; Env. de Paris, pl. v, f. 2. N.B. M. de lllainville considers these fonr last genera as more nearly related to the Terebratula::. M. Deshayes, on the contrary, Ann. des Sc. Nat. Dec. 1828, ap· proximates them to the Spondyli. |