80 HELICIDA. 
Var. I. bigranata. Smaller, thicker, with two 
denticles. 
Var. Il. albina. White. 
Genus VIT—VERTIGO. 
The members of this genus have only two tentacles, 
while those of the preceding genus have four. In 
order to aid the collector to identify these minute and 
very puzzling little shells, I have tabulated some of 
the most important differences of those which are 
dextral and furnished with teeth. (See Appendix B.) 
The ten species have been conveniently arranged as 
follows :— 
A. dextral, denticulated. ANTIVERTIGO, LILLJE- 
BORGII, MOULINSIANA, PYGM@A, ALPESTRIS, SUB- 
STRIATA. 
B. sinistral. PUSILLA, ANGUSTIOR. 
C. dextral, without tecth, EDENTULA, MINUTIS- 
SIMA. 
A. Dextrau, denticulate. 
1. V. ANTIVERTIGO (not reversed). 
Oval, thin, semi-transparent, glossy, rufous horn-colour ; 
whorls four and a half, tumid; spire short, abrupt; mouth 
semi-oval, contracted in the middle of the outer edge; 
7 
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