LAND SNAILS. 
147 
ob scums, with an oblong shell and a reflected 
peristome. 
Bulimus has persisted since the period of the 
Bembridge Limestone of the Upper Eocene. 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; e, g., 
Bulimus montanus, Clausiliabiplicata, G. Bolphii, 
Pupa substriata, Vertigo minutissima, V. angustior, 
Helix lamellata, and Succinea oblonga. 
Bulimus acutus — (the Banded Twist Shell) 
(PI. IX., fig. 83)—is a very conspicuous shell, 
from the contrast of colours presented by it, 
thus differing from its congeners, which have a 
uniformly coloured 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 Helicidce; 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 -■- 8 - -- 1 - g . 
10 0 
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 East of Ireland, 
