PHOLAS. 19 



periwincles, whelks, in large groups. I see that 

 you are examining the different appearance of the 

 pedunculated and the sessile Lepades. Linnaeus 

 made two divisions ; later writers have separated 

 them into several distinct genera, which will be 

 noticed when we attend to Lamarck's system. 

 The species are forty-five, of which several are 

 found on the British shores, as L. tulipa^ L. dia- 

 dema, L. tintinnahulum, L. halanus, L. ana- 

 tifera, he. The Indian, American, and Atlantic 

 oceans afford numerous species. 



" Third genus, Pholas. Generic character : 

 shell bivalve, gaping or divaricated, with several 

 smaller hinges situated upon the hinge ; hinge 

 recurved, with an incurved tooth." 



'' Father," said Charles, '' I must say that the 

 Pholas shell is very unlike those of the multivalve 

 division : I think it should rank with bivalves.''' 



" So many conchologists have judged; never- 

 theless it possesses more than two valves, and, 

 according to the system, it must be forced into 

 the division of multivalves. 



''The Pholades are found in company, but 

 each individual occupies a distinct habitation, 

 which the animal excavates for itself, either in 

 rocks, in wood, coral, or sponge ; but the finest 

 specimens are usually to be seen in chalk. In 

 proportion as the animal increases in size, it en- 

 larges the cavity in which it is stationed. The 



