312 Lamarck’s Genera of Shells. 
their base, slightly diverging above. One lateral tooth, distant 
from the hinge, on the anterior side, sometimes obsolete. Calli 
of the nymphe large, arched, terminated near the beaks by a 
pit. Ligament external, partly sunk under the beaks. 
The cyprinz are in general rather large shells, very like the 
veneres, and chiefly distinguished from them by having a com- 
pressed lateral tooth on the anterior side; by their large 
nymphe, generally terminated by an oval pit, sometimes singu- 
larly large near the beaks; by the ligament extending under the 
beaks, and there filling up the terminal pit of the nymph, and 
by having an epidermis, or drap marin, almost like the cyrene. 
In the latter respect, and from their sometimes almost obsolete 
lateral tooth, the cyprine are somewhat allied to the fresh- 
water conche. Probably many of them inhabit the sea at the 
mouths of rivers. 
Type. Cyprina Islandica*. (Venus Islandica. Linn.) 
Shell cordate, transversely striated, covered with an epi- 
dermis ; anterior side subangular: no anus. North Sea, at 
the mouths of rivers. 8 Species. PI. vi. Fig. 55. 
2. Cythereaf. 
Shell equivalve, inequilateral, suborbicular, triangular, or 
transverse. Four cardinal teeth on the right valve, three of 
them diverging, approximate at their base, and one, perfectly 
insulated, situated under the lunula. Three diverging cardinal 
teeth on the other valve, with a rather distant oval pit, parallel 
to the margin. No lateral teeth. 
The cytheree are distinguished from the veneres by having 
four cardinal teeth on one valve, and three teeth and the pit 
on the other. They are all sea shells, solid, in general variously 
and beautifully coloured, free, with the beaks curved, and 
moderately prominent. The oval insulated pit on the left 
valve corresponds to the insulated tooth on the right, having a 
* Of Iceland. Lamarck’s second species, his type, Cyprina gigas, being 
a fossil shell. 
+ Cytherean, a title of Venus, from the island Cythera, which was conse- 
crated to her. 
