CONCHOLOGY. 53 



D. deltoides. D. granosa. 



D. veneriformis. D. epidermia. 



D. Vittata. D. minima. 



D. variabilis.* D. fossar.* 



D. Californica.* 



9. Genus Capsa. PI. 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. Donaoides. 



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. 

 CoNCHACEA. Seven Genera. 



This family is divided into Conchx Mariiix, and Canchx 

 Fluviafiles. 



CoNCHas MAHiNiE. Four Genera. 

 1. Ctjprina. PI. VII. 

 Ani?nal. Thick, oval, foot compressed, falcifoFm, geniculated ; 

 5* 



