486 



MOLLUSKS : GASTEROPODS. 



F; g- 425- 



DENTALIAD.E. - - This Family 

 contains the Tooth-shells, of which 



i*, L. 



fossil species ; all marine. 

 CHITONID^E, OR CHITON FAMILY. - - This 

 Family comprises gasteropods which have 

 a shell composed of eight transverse imbri- 

 cating plates, lodged in a coriaceous mantle. 

 chiton richer, L. There are more than two hundred living 



New England. . .. , i i r 



species, and about one eighth as many tos- 

 sil ; all marine. 



Fig. 427. 



Fig. 428. 



Helix albolabris, Say. United States. 



Fig. 429. 



Fig. 430. 



Siiccinea olliquet, Say. 

 Western States. 



Fig. 43 1 - 



Pupa incana, Say. Florida. 



Buliiniis excclsus, Gould. 

 California. 



Helix albolalris, Say. 

 Northern States. 



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

 contains terrestrial gasteropods which are distributed 



