66 GENUS X. VENUS. 



difficulty in knowing- where to draw the Une of distinction 



between them. 



The animal is a Cockle, and differs but little from the ani- 

 mal of the Tellina, if we except perhaps Venus lapicida and 



lithophaga. 



Linnaeus describes 38 species, Gmelin has added 107, and 



Dr.Turton 9. Total, 154. 



Lamarck has placed Venus lithophaga, &c. in his genus 



Petricola, and Venus islamlica and some others in Cyclas, and 



Venus pensylvanica, &c. in Lucina ; and has divided the rest 



into five genera, as follows : 



Paphia. Shell sub-transverse, inequilateral, the valves shutting 

 close ; the cartilage internal ; the hollow for its insertion 

 is under the beaks, and between or beside the teeth of the 

 hinge {Venus divaricata. See pi. 2. /. 24). 



Venus. Shell nearly orbicular or transverse, with three hinge 

 teeth approaching, of which the side ones are more or 

 less diverging {Venus verrucosa Linn. See pi. 2.f. 25). 



Meretrix. Shell with two or three approximate hinge teeth 

 converging at the base, with a distant one under the 

 heart-shaped depression in one valve, and a hollow for its 

 reception in the other (Venus Meretrix. See pi. 3. f. 26). 



Venericardia. Shell nearly orbicular, inequilateral, with lon- 

 gitudinal ribs on the outer surface; two thick oblique hinge 

 teeth, not diverging (Venus iinbricata. See pi. 3. f. 27). 



Capsa. Shell transverse, with two hinge teeth in one valve, 

 and one bifid tooth intruded in the other (Venus de- 

 Jiorata Linn. See p/. 3. /. 28). 



