246 POPULAR BRITISH CONCHOLOGY. 



given to three very minute Helices. The shell of the 

 first is turreted, and has a keel of horny points round 

 the whorls ; that of the second is regularly ribbed ; 

 and that of the third is smooth^ with a conical spire. 

 H.fnsca has the shell transparent^ brown, depressed, very 

 slightly wrinkled, small ; H. rotundata is very de- 

 pressed, wrinkled, and with a large umbilicus ; H.j)ul- 

 chella is a minute white snail, with a very white, um- 

 bilicated shell, with a nearly circular mouth, living 

 under stones or in crevices in dampish places. 

 Two more minute species complete the list of this genus, 

 namely, H. umhiUcata, with the shell small, white, depressed, 

 with a large umbilicus ; and H. p^gmcea, microscopic. It 

 is of the H. umhilicata that Montagu observes : — " This 

 shell always affects such lofty places as the tops of houses, 

 without once being found near the base ; and in that situ- 

 ation its inhabitant braves equally the scorching beams of 

 the sun in summer and the frigid wind of winter, without 

 attempting to descend." 



ZOWITES. 



This . genus consists of small snails, which differ from 

 those of Kelix proper in having thin, glassy, flattened shells, 



