5 



wards, the aperture will lie to the right of the columella. 

 Shells coiled in this manner are " dextral," but one 

 occasionally finds a " sinistral " whelk with the spiral 

 reversed and the asymmetrical viscera developed on the 

 opposite side of the body. 



The shell may be regarded as a long cone coiled into 

 a spiral. Text-fig. 1 shows the terms in use for the 



Spire 



Whorl 



Body 

 Whorl 



Fig. 1. 



different parts. The apex is the oldest part of the shell 

 and often in gastropods presents important characters, 

 such as being coiled in the reverse direction. 



The whorls are in close contact and are about six or 



