202 PNEUMONOBRANCHIATA. 



Vertigo pygmsea. Ferus. Tab. Moll. 64. ; Turton, 

 Man. ed. 1. f. 83.; Alder, Mag. Zool Bot. ii. 

 112. 



Helix Isthima cylindrica. Gray, Med. Repos. 

 1821. 239. 



Turbo sexdentatus jun. Montag. T. B. 337. 



Alaea vulgar is. Jeffreys, Linn. Trans, xvi. 359. 



On dry barren hills, under stones. 



Animal blackish grey ; tentacles very short. 



Shell a line long, dark brown, semitransparent ; 

 spire composed of five rounded and nearly smooth 

 volutions ; aperture somewhat triangular, with usually 

 five teeth, two on each lip, and a central one on the 

 upper part; peristome thin, whitish when the shell is 

 perfect, slightly reflected and forming an umbilicus, 

 with a longitudinal external rib on the outer lip. 



72. 4. VERTIGO alpestris. Alpine Whorl Shell, (t. 



f. 141.) Shell cylindrical, pale horn-colour, 

 transparent, striolate, with five whorls a little 

 rounded ; aperture semicircular, outer lip slightly 

 bent and reflected ; teeth four, situated as in V. 

 pygmcea. 



Vertigo alpestris. Ferussac, MSS.; Alder, Mag. 

 Zool. fy Bot. ii. 112. 



Inhab. old walls. 



Differs from V. pygm&a, to which it is very like, in 

 being more cylindrical and slightly striated. The 

 shell is about one tenth of an inch long, half as 

 broad. 



73. 5. Vertigo substriata. Six-tooothed Whorl Shell. 



(t. 7. f. 84.) Shell subcylindrical, ventricose, shin- 



