Lamarck’s Genera of Shells. 311i 
Lamarck divides the species into (1) Those with serrated 
lateral teeth, and (2) Those whose lateral teeth are entire. 
Type. Cyrena cor*. 
Shell elongated-cordate, inequilateral, tumid, scalariform- 
sulcate ; nates prominent, involute. 
Brought by Olivier. 7 Species of the first division, 4 of 
the second. PI. vi. Fig. 53. 
3. Galathea. 
Shell equivalve, subtriangular, covered with a greenish epi- 
dermis. Cardinal teeth furrowed; two on the right valve, 
approaching at their base with an uneven cavity in front, three 
on the other valve disposed in a triangle, the middle one ad- 
vanced, separate, large and callous. Lateral teeth distant. 
Ligament external, short, projecting, turgid. Nymphe promi- 
nent. 
The galathea is distinguished from the cyrena by the pecu- 
liar form of its cardinal teeth, The muscular impressions are 
lateral, and appear double on each side. 
One Species. Galathea radiatat. (A variety of this genus is 
the venus subviridis, of Gmelin.) 
Rivers of Ceylon. Arare shell, milk-white under the epi- 
dermis, with violet-coloured spots near its base, and two to 
four violet rays. PI. vi. Fig. 54. 
C. Marine}. (4 Genera.) : 
Generally no lateral teeth; rarely, the whole shell, except 
the beaks, covered with the drap marin, The marine conche 
are extremely numerous, varied, and often elegant, Linnzus 
classed them all under the genus Venus. 
1. Cyprina§. 
Shell equivalve, inequilateral, obliquely cordate, beaks ob- 
liquely curved. Three unequal cardinal teeth, approaching at 
_ * Heart, Lamarck’s third species ; his type is C. trigonella. 
+ Radiated. + Marine. 
§ Cyprian. The island of Cyprus was consecrated to Venus, 
