VERTIGO. 253 



Continental naturalists of repute have also made inde- 

 pendent observations and arrived at the same conclu- 

 sion. An exotic species (V. rupestris) is half as large 

 again as Pupa marginata ; and yet, according to Moquin- 

 Tandon, not a trace can be detected in this species of 

 Vertigo of the lower tentacles which are possessed by all 

 the species of Pupa. The shell of Vertigo differs also in 

 a corresponding degree from that of Pupa. The spire is 

 shorter ; and when the mouth is furnished with teeth (as is 

 commonly the case) the outer Up is contracted. It would 

 therefore seem to be quite as reasonable that Vertigo 

 should be separated from Pupa, as Bulimus from Helix. 

 The line of demarcation in either case is confessedly 

 slight. The value of such generic distinctions wiU pro- 

 bably not be admitted by all naturalists ; and unfortu- 

 nately there is no Court of Science to which an appeal 

 can be made for an adjudication of the point. 



The typical and original species ( V. pusilla) has the 

 spire reversed or sinistral, from which character the name 

 now borne by the genus was derived. 



A. Shell dextral, barrel-shaped : mow^/i furnished with teeth. 

 1. Vertigo antiverti'go*, Draparnaud. 



Pupa antivertigo, Drap. Tabl. Moll. p. 57, and Hist. Moll. p. 60, pi. iii. 

 f. 32, 33 ; F. & H. iv. p. 109, pi. cxxx. f. 7. 



Body thick, lustrous and dusky, greyish-black with a tinge 

 of slate -colour or brown, covered with exceedingly minute 

 black or dark tubercles : snout short, but somewhat produced : 

 tentacles rather close together, subcyhndric ; bulbs forming one- 

 third of them, oval and obtusely pointed: foot oblong and 

 narrow ; edges very light grey and finely speckled with black ; 

 tail rather blunt. 



Shell oval, thin, semitransparent, very glossy and of an 



* Kot reversed. 



