VERTIGO. 259 



It makes, like its congeners, a filmy epiphragm, but 

 which is not iridescent. It may be in some degree 

 considered a subalpine form, as it occurs at considerable 

 heights. Dr. Johnston found it at the top of a moun- 

 tain in East Lothian at an elevation of 1200 feet, and 

 M. Puton on the Vosges at a height of 1640 feet. The 

 teeth do not appear to be formed in any of the whorls 

 except the last. They project into the mouth at right 

 angles, so as to present a chevaux de frise against all 

 intruders. 



This species may at once be known from V. antivertigo, 

 as well as from V. Moulinsiana, by its more cylindrical 

 or narrower shape, and from the former by its having 

 only a single tooth on the pillar, instead of two or three 

 as in that species. The outer lip is also not contracted 

 and angulated as in V. antivertigo. The other points 

 of difference between the present species and V. Mou- 

 linsiana have already been noticed in the account of 

 that species. 



Montagu was evidently acquainted with the present 

 species, but confounded it with V. antivertigo (his Turbo 

 sexdentatus), in describing which he says, "younger 

 shells have only four teeth." I may observe that the 

 fifth or smaller tooth, which is placed within the outer 

 lip and close to the pillar lip, is seldom wanting, although 

 not so conspicuous as the others, and that five is the 

 usual, and four the exceptional number of teeth. 



4. V. ALPES'TRIS *, Alder. 



V. alpestris, Alder, Trans. Nat. Hist. Soc. Newc. ii. p. 340. Pupa 

 pygmcea, var. alpestris, F. & H. iv. p. 107, pi. cxxx. f. 6. 



BODY light-strawcolour : tentacles and foot longer than in 

 V. pygmcea. 



* Inhabiting high land. 



