WATER-BKEATIilXG SNAILS. 



:i3 



the Pyrula and Tritonium of the coast of the United 

 States, and the Frog Shell of y\ustralia, are some of 

 the principal ones. The ancients obtained the Tyrian 

 purple dye from the Murex Gastropods. 



Fig. 367. — Pyrula. Much reduced. 

 Coast of United States. 



Fig. 366. — Murex. Much 

 reduced. Moluccas. 



Fig. 368. — Tritonium. Coast Fig. 369. — Frog Shell, or Ranella. 

 of New England. Reduced. Australia. 



Whelks. 



The Whelk is one of the most common of the Gas- 

 tropods. Fig. 370 shows one species as it appears 



