228 POPULAR CONCHOLOGY. 



varices three or more, spiny or roughs and con- 

 nected; mouth round and small; operculum 

 horny. Animal, head having two long tenta- 

 cula furnished with eyes ; foot round, and gene- 

 rally short. — 66 species recent, and 15 fossil. 



These shells are found in nearly every part 

 of the world, and are remarkably curious : the 

 finest species come from tropical countries. 

 The Murex tenuispina, or Venus's Comb, as it 

 is called, is entirely beset with long sharp 

 spines, which the animal has the power of dis- 

 solving and replacing by a smooth and even 

 surface, whenever it finds it necessary, in en- 

 larging its shell, to remove them. This faculty 

 is also possessed by other species, but it is very 

 conspicuous in the tenuispina. In specimens 

 in which the process is going on, there may be 

 observed a notch formed by this means in the 

 base of the spines, the completion of which 

 eventually causes them to separate from the 

 shell.* 



95. Triton. — Shell oblong ; canal short ; 

 varices placed alternately on each whorl, often 

 considerably distant from each other, and never 



* Gray. 



