BIVALVIA. 205 
Gen. Char. Shell ovate or oblong, equivalved, inequilateral, somewhat compressed. 
Hinge composed of three cardinal teeth in one valve, and two or three in the other. 
Muscular impressions ovate, with a deep palleal sinus. Ligament external. 
Animal oblong; the mantle closed all round with the exception of a small opening 
in front for the passage of the compressed and lanceolate foot ; siphons unequal, dis- 
united at about half their length; extremities ornamented with a double row of fringes. 
The arrangement of dental characters in what constitutes this genus, as well as 
the general form of the shell, approach so closely to those of Zapes, that it seems more 
entitled to a position amongst the Venus family than to any other, and so far as the 
form of the foot of the animal or its siphons may determine its connections, it does 
not any further justify a removal; its habits certainly resemble those of Sazicava, but 
the selection as a habitat in holes, formed in rocks, is not peculiar to one family, as 
Bivalves of very different forms have been found located in such situations : and habits 
alone are not sufficient for the uniting into one family those Bivalves which possess 
them; perhaps, after all, this genus as it now stands will be found to possess no 
sufficient claims for a separate position, and may probably be hereafter united with 
Tapes. 
As a genus it contains but very few species, and little is at present known respecting 
its exotic allies in the recent state, and nothing in the fossil of an older date than the 
Upper or Middle Tertiaries. 
1. VENERUPIS IRUS. Linneus. Tab. XIX, fig. 6a, 4. 
Donax Inus. Linn. Syst. Nat., ed. 12, p. 1128, No. 111, 1767. 
—- — Poli. Test. Sicil., vol. i, t. x, figs. 1, 2, and vol. ii, p. 83, t. xix, figs. 25, 26, 
1795. 
Cunevs rouratus. Dacosta. Brit. Conch., p. 204, pl. xv, fig. 6, 1778. 
Tpriina CornuBiEeNnsis. Penn. Brit. Zool., ed. 4, vol. iv, p. 75, No. 35. 
Venus Irnvs. Brown. Illust. Brit. Conch., pl. xx, fig. 9, 1827. 
—  rvupestris? Broc. Conch. Foss. Subap., p. 599, t. xiv, fig. 1, 1814. 
Venenrvris Invs. Lam. An. sans Vert., t. v, p. 507, 1818. 
— —  Payr. Catal. Moll. Cors., p. 35, 1826. 
— — Phil. En. Moll. Sic., vol. i, p. 21, vol. ii, p. 20. 
— — For. and Hanl. Hist. Brit. Moll., vol. i, p. 156, pl. vii, figs. 1—3, and 
pl. G, fig. 2. 
= — Midden. Malac. Rossic., p. 567. 
Perricota Irus. Turt. Brit. Biv., p. 26, t. ui, fig. 14, 1822. 
= rupESTRIS? Dubois. Coq. Foss. Wolh. Pod., pl. vii, figs. 3, 4, 1831. 
Putiastra Irvs. Brown. Ilust. Brit. Concb., 2d ed., pl. 37, fig. 9. 
Capsa Irnvs. ‘Leach, 1818.’ Ann. and Mag. Nat. Hist., vol. xx, p. 272. 
? Eneye. Method., pl. 262, fig. 4. 
Spec. Char. Testa ovato-oblonga, vel subtrapezoidea, crassa ; postice longiore et latiore, 
subangulata ; lamellatd, lamellis transversis, interstitiis radianter striatis ; dentibus tribus 
in utraque valvd ; sinu palliari magno, subangulato. 
