48 COKBULA. LITHOPHAGA. 



Crassatella Mactra. 



Erycina .. 



Ungulina 



Solenomya Mya. 



Amphidesma Telllna. 



^^ Crassatella is a genus from the seas of New 

 Holland. The shell is very thick, with a brown 

 epidermis. A fossil species is found at Hord- 

 well cliff. There are several species also found 

 in the chalk. Mactra, Lutraria, and Ery- 

 cina are found in a fossil state. Crassatella 

 sulcata is common in London clay. 



" The family Corhula contains two genera. 



Corhula 



Pandora Tellma. 



" Corbula comes chiefly from the Asiatic Seas. 

 There is 07ie species, formerly Alya inequivalvis, 

 from the British Ocean ; fossil species several. 

 Pandora rostrata is British, and is said to be met 

 with at Weymouth. It is a pretty shell. The 

 ligament of these is internal. 



" Lithophaga includes 



Haxicava Mytilus. 



Petricola. 



Venerupis, or Venus of the rocks. 



