140 LAND AND ERESH-WATER MOLLUSKS. 
sometimes found without the longitudinal plates 
which generally cover the shell. 
Helix lapicida— (the Variegated Bock Snail) 
(PI. VIII.,, fig. 79)—the technical name, signi¬ 
fying “a stone-cutter/^ is very inappropriate, and 
was given to this species by the great Linnaeus, 
from an erroneous idea that it ate or excavated 
limestones. 
The shell is depressed, lens-shaped, convex 
above and below, with a sharp keel on its outer 
circumference; the aperture is longitudinally oval 
and angular; the white and reflected peristome is 
united all round; the edge is acute but not 
thickened. The colour of the shell resembles 
that of H. rotundata , is yellowish-red, irregularly 
streaked across the whorls with reddish-brown ; 
the surface is also striated with closely-set lines 
of growth; the umbilicus is large. The dental 
formula is 40 i 1 5 ‘q ~. 
This snail is truly a woodland species, and 
is confined to the central and southern counties 
of England ; it is found as far north as Brocker- 
dale near Pontefract. It has a wide range in 
Europe. 
It has been supposed to be restricted to lime¬ 
stone tracts, but I have found it very general in 
the woods of the Wealden district, where the 
rocks are especially characterized by the absence 
of the calcareous element. In Gloucestershire, 
