486 



MOLLUSKS: GASTEROPODS. 



Fi s- 425- 



Dentalium dentalis, L. 

 Atlantic. 



DENTALIAD.E. This Family 

 contains the Tooth-shells, of which 

 there are fifty living, and seventy 

 fossil species ; all marine. 



OR CHITON FAMILY. This 



Family comprises gasteropods which have 

 a shell composed of eight transverse imbri- 

 cating plates, lodged in a coriaceous mantle. 

 There are more than two hundred living 

 species, and about one eighth as many fos- 

 sil ; all marine. 



Fig. 427. 



Chiton ruber, L. 

 New England. 



Fig. 428. 



Helix albolabris, Say. United States. 



Fig. 429. 



Fig. 430. 



Succinea obliqna, Say. 

 Western States. 



Fig. 431. 



Pupa incana, Say. Florida. 



Bulimiis excelsus, Gould. 

 California. 



Helix albolabris, Say. 

 Northern States. 



HELICID^E, OR LAND-SNAIL FAMILY. This Family 

 contains terrestrial gasteropods which are distributed 



