14 WESTERN SERIES OP READERS. 



on the land and in the sea, that have no shells 

 whatsoever. 



The third class of mollusks have no heads at all, 

 though they all have mouths and lips, and a few 

 of them have eyes also. They live within a pair 

 of shells, which they can open or close at will. 

 Most of them dig burrows with a fleshy foot 

 shaped like a hatchet, and hence they are called 

 Pel-e-cy-pods, meaning hatchet-footed creatures. 



Besides these three classes there are certain 

 other mollusks which are seldom seen in these 

 times, though long before man lived on the earth 

 they were very numerous. We need not think of 

 them now, but when you study geology you will 

 learn a great deal about them, for very many of 

 their shells are found preserved in the rocks. 



As for the three long Greek names, they are all 

 very proper to know, but for our purposes suppose 

 we call the three classes Swimmers, Creepers, and 

 Bivalves; for the Cephalopods swim, the Gastero- 

 pods creep, and the Pelecypods have double shells. 



Now, leaving the Swimmers to take care of them- 

 selves in the ocean waves, we may group all of the 

 Creepers and Bivalves into three great divisions, 

 according to their favorite places of habitation. 

 We will nfime them Rock-lovers, Sand-dwellers, 

 and Mudsills. 



