CONCHIFERA. 733 
sec, Série, 111. 1835, pp. 193—213, Pl. virt.; CANTRAINE, who places this 
genus, on account of the mantle for the most part united, not in this family, 
but in Byssomya, names it Mytilina. Ann. des Sc. nat., sec. Série, v1. pp. 
302—312. It agrees, however, very closely with Mytilus, as well in the 
shell as in the animal. 
Family VI. <Arcacea. Mantle cloven anteriorly, not produced 
into a trachea. Foot large, in some serving for creeping, in others 
furnished with byssus horny, lamellose, not divided into filaments. 
Branchiz composed of loose filaments. Shell regular, with points 
remote. Hinge with numerous teeth arranged in a row. Two 
muscular impressions remote. 
Arca L. (in part). Hinge linear, straight. Shell transverse, 
inequilateral, with points distant, a large area intervening. Animal 
(Daphne Port) with foot compressed, cloven longitudinally, mostly 
adhering by means of lamellose, horny byssus to marine bodies. 
Sp. Arca Now L., Rumpx. Amb. Rariteitk. Tab. 44, fig. p, Encycl. méth., 
Vers. Pl. 303, Buatnv. Malacol. Pl. 65, fig. 2; in the Mediterranean and 
the Atlantic; the Noah’s Arc; the boat-like form occasioned the generic 
name.—Arca tortuosa L., RumpH. 1. 1. Tab. 47, fig. K, Encycl. méth., Vers. 
Pl. 305, fig. 1, Buarnv. Malac. Pl. 65 bis, fig. 1, from the Indian Ocean, 
&c, A very numerous genus, of which also fossil species occur, some in 
secondary, but the most in tertiary formations. 
Cucullea Lam. Shell ventricose. Hinge terminated at each end 
by ribs exsert, parallel to the margin, various in number. 
Sp. Arca cucullus GMEL., Cuculleea auriculifera Lam., Buatnv. Malac. Pl. 
65, fig. 4; from the Indian Ocean. The fossil species of this small group 
are the more numerous, since amongst the animal world now living, only 
this single one is known. 
Pectunculus LAM. (Species of Arca L.). Shell orbicular, thick, 
shut. Hinge arcuate, with teeth oblique, the median obsolete. 
Animal (Axinea Pout) with foot hatchet-shaped, serving for creep- 
ing, very large, compressed, not byssiferous ; heart single. 
Sp. Pectunculus pilosus LaM., Arca pilosa L. (and glycimeris in part), Bo- 
NANNI Recreat. Mentis et Oculi, Rome, 1684, fig. 80, Pox Test. utr. Sic. 
Tab. 26, figs. 2, 3, GuéRIN Iconogr., Moll. Pl. 27, fig. 6, DrsHAYES Con- 
chyl. Pl. 34, figs. 23, 241;—Pect. glycimeris Lam., Desn. 1. 1, figs. 21, 22, 
1 The shells of this species are used by the Sicilians, according to the account of 
Pout, for making cameos. 
