100 MOILUSCA. 



their shell is of a very different form, beinej a triangle, of which the 

 obtuse angle is at the summit of the A'^alves, and the base at their 

 edge, and of which the shortest side is that of the ligament, or the 

 posterior side, a rare circumstance in this degree, among bivalves. 

 They are generally small, and prettily striated from the summits to 

 the edges; their animal — Peeon^a, Poll, is furnished with long tubes 

 which are received into a sinus of the mantle. Some of them are 

 found on the coast of France*. The 



Cyclas, Briig, 



Separated from Venus by Brugiere, like the Cardia and Donaces, 

 has two teeth in the middle of the hinge, and before and behind, two 

 salient, and sometimes crenulated plates ; but the shell, as in several 

 species of Venus, is more or less rounded, equilateral, and trans- 

 versely striated. The animal has moderate tubes. The external 

 tint is usually grey or greenish. The Cyclades inhabit fresh water. 



One species, the Tellina cornea, L.; Chemn., VI, xiii, 133, is 

 very common on the coast of France f. M. Lamarck separates 

 the 



"Where the shell is thick, slightly triangular and oblique, covered 

 with an epidermis, and otherwise distinguished from the Cyclades by 

 having three cardinal teeth. The Cyrenee also inhabit rivers, but 

 there are none in France \. 



Cyprina, Lam. 



Also separated from the Cyclades by Lamarck; the shell is thick, 

 oval, Avith recurved summits, and three stout teeth ; further back is 



* Donax t-vgosa, Chemn., VI, xxv, 250 — 252; — D fruncuhis. lb,, xsvi, 253, 

 254 ; — D. striata, Kuorr.. Delic, VI, xxviii, 8 ; — D. denficuhifa, Cheian., I, c. 256, 

 257; — D. faba, lb., 266; — D. s/mjosa, lb., 258. Fossil species are nuinerous in 

 the environs of Paris. See Lamarck, Ann. du Mus., VIII, 139, and Deshayes, 

 Coq. foss. des Env. de Paris, I. pi. xvii, xviii. 



The Donax irrrgvlaiis, from the Environs of Dax, described by M. Bastorat in 

 tlie M(-m. de la Soc. d'llist. Nat. de Paris, t II, pi. iv, f. 19, A, B, is the type of a 

 new genus lately established — Bullet, de la .Soc. Lin. de Bourdeaux, II, by M. 

 Charles Desmoulins, under the name of Gratklupia. It is distinguished from the 

 Donaces by the presence of several dentiform lamellse which accompany the cardinal 

 teeth. 



Several species of J'cnus, and some Macfra, are mixed with these true Donaces by 

 Gmelin. 



f Add Telliiia rivalis, Miill., Drap., X, 4, 5 ;~r- Cyclas foniinalis, Drap., lb., 

 8 — 12 i—Cycl. caliculata, lb., 13, i4 ■,—TeIlina lacustris, Gm., Chemn., XIII, 135 ; 

 — Tell, amnica, lb., 134; — Tell, fluviutilis ; Tell, fluminalis, Chemn., VI, xxx, 

 320. 



X Tell, fluininea, Chemn., lb., 322, 323 ; — Venxis coaxans, Id., xxxii, 336, or 

 Cyrena ceylanica, Lam., Encyc. Method., pen., pi. 302, f. 4; — Venus horealis, Id., 

 VII, xxxix, 312, 314 ; — Cyclas cardiniana, Bosc, Shells., Ill, xviii, 4. Fossil spe- 

 cies abound near Paris. See Deshayes, Coq. Foss., I, pi. 18, l< 



