CONCHIFERA. 



227 



a deep sinus in the pallial impression. Animal unknown. 



— Few species ; also fossil 



From Jamaica, New Holland, the Indian and American 

 seas. 



Capsa. Brug. (Capsa Lain. ; Capsula Schum. ; San- 

 guinolaria Desk.) — Shell oval, globose, both ends gaping, 

 equivalve, but rather inequilateral ; ribbed in rays ; liga- 

 ment exterior, and on the shortest side; two cardinal 

 teeth in each valve, none lateral ; margins not crenulated ; 

 pallial impression with a deep sinus. Animal unknown. 



— 2 species. 



India and Brazil produce these shells, which lie buried 

 at small depths in the sand, one species is the Venus dejlo- 

 rata of Linnaeus. 



(Marine genera, with the ligament internal.) 



MactPwA. Lin. — Shell mostly thin, oval, transverse, 

 with thin cardinal and lateral teeth, one 

 of which, shaped like the letter V, 

 has the point near the boss locking into 

 a pit in the other valve : cartilage pit 

 triangular ; valves slightly inequilateral, 

 and gaping a little on each side ; bosses 

 protuberant. Animal triangular or ob- 

 long ; its mantle freely open in front as far as the siphons ; 

 the margin more or less distinctly fringed ; the siphons are 

 united to their extremities, which are surrounded with 

 fringes of simple cirrhi ; the foot is strong, changeable in 

 shape, linguiform, and geniculate : the labial tentacles are 

 long, pointed, and pectinated on their inner sides ; the 

 outermost branchial leaflets in each pair is shorter than the 

 other. * — More than 50 species; also fossil. 



The Mactra live in the sand, and are found in all parts 



* Forbes's British Moll. 

 Q 2 



