80 POPULAR CONCHOLOGY. 



callosity) which often projects, and the valves 

 either do not gape, or so slightly that it is al- 

 most imperceptible. There are never more 

 than two cardinal teeth on the same valve, and 

 only some of the genera have lateral teeth. 

 These shells are all litoral, and bury them- 

 selves in the sand. — There are 8 genera. 



35. Sanguinolaria. — Shell transverse, 

 equivalve, inequilateral, 

 slightly gaping at both 

 ends; hinge having in 

 each valve two teeth 

 approaching each other. 

 Animal unknown. — 4 species recent. From 

 Jamaica, New Holland, the Indian and Ame- 

 rican seas. 



36. Psammobia. — Shell transverse, oval, 



slightly gaping at each end ; hinge having two 

 teeth on one valve, and one on the other; 



