528 



Mollusca. 



ing classes, and are caught chiefly in the winter months. 

 Their size varies from five or six inches to half an inch 

 in diameter. The shell is generally white; it has 

 twenty-six longitudinal ridges, is transversely wrinkled, 

 and has somewhat imbricated stria3. The foot of these 

 animals is largely developed, and is to them a most im- 

 portant organ, as they use it not merely for progression, 

 but in the excavation of hollows in the sand or mud in 

 which they dwell. 



The Chama, which is akin to the cockle, was used by 

 the ancients to engrave various figures upon, from which 

 circumstance those small bas-reliefs, so valued now, 

 have obtained among the Italians and collectors the 

 name of Cameos. The shells of some of these are 

 decorated with red or yellow stripes, diverging from 

 the hinge, and spreading to the edges. The Giant 

 Chama has been found to weigh more than five hundred 

 pounds, and the oyster-like animal within was large 

 enough to furnish a meal for twenty men. The animals 

 which inhabit these shells are sometimes called Clams. 

 The shells are often used in Catholic countries for 

 containing holy water. 



THE PHOLAS. (Pholas dactylus.) 

 THIS is a shell of a rather elongated form, gaping at both 



