CONCHOLOGY. 53 
D. deltoides. D. granosa. 
D. veneriformis. D. epidermia. 
D. Vittata. D. minima. 
D. variabilis.* D. fossar.* 
D. Californica.* 
9. Genus Capsa. Pl. VII. 
Animal. As above. 
Shell. Transverse, equivalve, valves approximate and close ; 
three primary teeth in the right valve, and a single bifid tooth in 
the left, inserted into a cavity in the opposite one; no lateral 
teeth ; ligament external and on the short side, as in Donax, from 
which it was separated by Lamarck, on account of the peculiarity 
of the hinge. Inhabits the Indian Ocean. ‘Three species. 
Capsa levigata. Capsa Braziliensis. 
C. Donavides. 
10. Genus Crassina. PI. VII. 
Animal. As above. 
Shell. Distinguished from the Venus by having only two teeth 
on each valve, and from the crasatella by the position of the liga- 
ment ; solid, sub-orbicular, thick, hinge with two strong diverging 
primary teeth in the right valve, and two unequal ones on the 
‘other ; ligament external. Inhabits the Scottish and Devonshire 
coasts. One species. 
Crassina Danmoniensis. 
FAMILY IX. 
Concuacea. Seven Genera. 
This family is divided into Conchz Marine, and Conchz 
Fluviatiles. 
Concuaz Marina. Four Genera. 
t.-Cyprina. Pl. VIL. 
Animal. Thick, oval, foot compressed, falciform, geniculated 
5x* 
