LAND SNAILS. 147 
obscurus, with an oblong shell and a reflected 
peristome. 
Bulimus has persisted since the period of the 
Bembridge Limestone of the Upper Hocene. B. 
montanus and B. obscurus are both fossils of the 
Pleistocene marls; the former at Clacton and 
Orton, the latter at Copford. 
Many of the pulmoniferous snails now rare in 
this country were formerly abundant, and had a 
wider geographical range than at present; ¢. 9., 
Bulimus montanus, Clausilia biplicata, C. Rolphii, 
Pupa substriata, Vertigo minutissima, V.angustior, 
Helix lamellata, and Suecinea oblonga. 
Buummus acutus— (tke Banded Twist Shell) 
(Pl. [X., fig. 83)—is a very conspicuous shell, 
from the contrast of colours presented by it, 
thus differing from its congeners, which have a 
uniformly coleured shell. The shell is cylindrical, 
acute, with eight or nine rounded whorls, gra- 
dually increasing in size; the aperture is small, 
and the outer lip is thin and plain, not reflected, 
as in the majority of the Helicidw; it rarely 
exceeds half an inch in length. The colour is 
generally yellowish-white, with bands of reddish- 
brown to black. The dental formula is +825, 
It is a somewhat local species, and inhabits 
the calcareous downs and the sandy pastures and 
dunes on the sea-coast, especially in the South 
and West of England, North and Kast of Ireland, 
L2 
