118 



GASTEOPODA. 



tentacles ; foot rounded in front, its sides moving 

 alternately. 



P. puUus. Fig. 174 ; f . 



174 



175 



176 



TrocJms (Lmn.). Top. Shell pyramidal, nearly 

 flat at the base ; aperture oblique, somewhat four- 

 sided ; pearly ; operculum horny, many-whorled. 

 Animal with two minute head-lobes, large neck- 

 lappets, side-lobes, and filaments. 



Adeorhis (Wood). Shell minute, depressed, 

 few-whorled, deeply umbilicated ; operculum shelly, 

 many-whorled. 



A. sub-carinata. Fig. 176 ; f . 



