Lamarck’s Genera of Shells. 313 
different direction from the cavities which receive the three 
cardinal teeth. Two of the cardinal teeth are often approxi- 
mate; the third more diverging, being placed on the anterior 
side, under the nymphe. 
The species are subdivided into, (1) Shells, with the margin 
entire, and (a) the anterior cardinal tooth having a striated 
canal, or indented border—12 species; or (b) the canal not 
striated, nor border indented—S0 species; (2) Shells, with the 
internal margin of the valves crenate, or indented: 16 species. 
Type. Cytherea lusoria*. (Venus lusoria. Chemn.) 
Shell ovato-cordate, smooth, white ; chestnut brown zones, 
interrupted in the middle; anterior cardinal tooth, with a 
striated canal. China Seas. In all 78 recent species, and 9 fos- 
sil. Pl. vi. Fig. 56. 
3. Venus. 
Shell equivalve, inequilateral, transverse, or suborbicular. 
Three approximate cardinal teeth on each valve; the lateral 
teeth diverging at the summit. Ligament external, covering 
the scutcheon. 
The veneres are amongst the most beautiful of the conchifera. 
They are not distinguished by their general form from the cy- 
therez, wherefore, to ascertain their genus, we must examine the 
hinge; they are, however, more commonly transverse than or- 
bicular. They are all sea-shells, free and regular. The middle 
cardinal tooth, which is often bifid, is straight, whilst the lateral 
are oblique and diverging ; a few species have, nevertheless, all 
the cardinal teeth almost straight. 
The animal of the venus appears to have the mantle open 
in front, allowing a passage to two siphons, more or less pro- 
jecting externally, Its foot is compressed, and lamellar, vari- 
able in size and form. 
The veneres live in the sand, at a small distance from the 
shore. They are found in all the seas, but are most numerous 
and varied in those of hot climates. 
* As being used in play, for which purpose the Chinese and people of 
Japan employ this shell. They paint the inside of various colours, 
