MOLLUSCA OR UNIVALVES. 239 



species, 



latitudes, particularly those of America; like 

 the last genus they frequent the rocks. 



105. Concholepas. — Shell thick and 

 rough; apex inclined to- 

 wards the left lip ; mouth 

 very large, with a slight 

 notch at the base ; right 

 lip having two teeth at 

 the base ; an operculum. 

 Animal like the Purpura. — -Only 

 recent. 



Of this singular genus the only species known 

 is very abundant on the coasts of Peru and 

 Chili, and is known by the name of Concholepas 

 Peruvianus. It often grows to a large size, and 

 although not beautiful is a curious shell. In its 

 shape it has more analogy with the Patella fa- 

 mily than any other ; but from the different 

 form of the animal, and the circumstance of its 

 constructing a large operculum, it must be 

 placed amongst the Purpuridce. The shell is 

 two or three inches in length. 



106. Harpa. — Shell oval, smooth, and 

 marked with parallel longitudinal ribs, the up- 



