132 



116. VALVATA Planorbis. Shell flat above, and 

 deeply umbilicate beneath. 



Valvata Planorbis. Drap. p. 41. t. I./. 34, 35. 

 Brard,p. 186. t. 6./. 18, 19. 



Shell smaller than the last, from which it differs in 

 being of a more transparent whiteness, and not 

 being concave or sunk in the upper surface ; the 

 umbilicus is also narrower and deeper. 



Found with the last, but more rarely. 



117. VALVATA minuta. Shell a little convex above, 

 and umbilicate beneath. 



Valvata minuta. Drap. p. 48. t. I./. 3638. 

 Helix serpuloides. Mont. Suppl. 147. t. 21. f. 3. 

 Turbo serpuloides. Turt. Diet. p. 228. 



Shell exceedingly minute, with two or two and a half 

 volutions, very finely striate, a little convex on the 

 upper surface, and deeply umbilicate beneath. 



Very much allied to this species is the Turbo depres- 

 sus, which we take from the marine rocks in 

 Devonshire : but independently of the latter being 

 a salt-water shell, the operculum is not spirally 

 striate, and the animal wants the crested appendage 

 in the middle of the head. 



In ditches and marshes. 



