100 
MOl UTPCA. 
their sliell is of a very different form, beins? a triangle, of which the 
obtuse angle is at the summit of the valves, 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 — P ep.onvEa, Poll, is furnished with long tubes 
Avhich are received into a sinus of the mantle. Some of them are 
found on the coast of France*. The 
Cyclas, Brttg. 
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 
. Cyrena, Lam. 
Where the shell is thick, sliglitly triangular and oblique, covered 
with an epidermis, and otherwise distinguished from the Cyclades by 
having three cardinal teeth. The Cyrcnae 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 hack is 
* Donax rugosa, Chemn., VI, xxv, 250—252 ; — D. trunnilus. Ib,, xxvi, 253, 
254 ; — D. striata, Knorr.. Ddic., VI, xxviii, 8 ; — D. denticuluta, Chemn., I, c. 256, 
257 ; — D. faha, Ib., 266 ; — D. spinosa, Ib., 258. Fossil species are numerous in 
the environs of Paris. See Lamarck, Ann. du Mus., VIII, 139, and Deshayes, 
Coq. foss. des Eiiv. de Paris, I, pi. xvii, xviii. 
The Donax irregularis, from the Environs of Dax, described by M. Bastorat in 
the 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 Gratelupia. It is distinguished from the 
Donaces by the presence of several dentiform lamella; which accompany the cardinal 
teeth. 
Several species of J'enus, and some Mactrce, are mixed wdth these true Donaces by 
Gmelin. 
f Add Tellina riralis, Miill., Drap., X, 4, 5; — Cyclas fontinalis, Drap., Ib., 
8 — 12 ; — Cycl. caliculata, Ib., 13, i4 ; — Tellina lacustris, Gm., Chemn., XIII, 135 ; 
— Tell, amnica, Ib., 134; — Tell. Jluviatilis ; Tell, fluminalis, Chemn., VI, xxx, 
320. .5:1 
J 2'ell. fluminea, Chemn., Ib., 322, 323 ; — Venus coaxans, Id., xxxii, 336, or 
Cyrena ceylanica, Lam., Encyc. Method., pen., pi. 302, f. 4 ; — Venus borealis, Id., 
VH, xxxix, 312, 314 ; — Cyclas cardiniana, Bose., Shells., HI, xviii, 4. Fossil spe- 
cies abound near Paris. See Deshayes, Coq. Foss., I, pi. 18, 1 < 
