LAND SNAILS. 111 
The diameter of the pyramidal shell is a tenth 
of an inch, and the height nearly the same. The 
dental formula is 722-22. 
It is widely distributed, though seldom met 
with in abundance in any one locality. It in- 
habits beneath stones in quarries and old walls, 
and among moss and herbage in woods and moist 
pastures. 
There is a very striking resemblance between 
H. fulva and H. chersina of America, yet these 
species have never been united. 
All the above-mentioned species of Helicella 
are fossilized in the Pleistocene fresh-water marls 
at Copford, Clacton, &c. 
Genus HELtx. 
The British Helices are comprised in 25 species, 
which I have arranged into artificial groups, 
founded upon characters afforded by the adult 
shells. These are exhibited in the following 
table, which is merely intended to assist the 
student in discovering the species :— 
hortensis 
» umbilicated 
9 Shell more or less globular 
: », depressed aes 
Shell imperforated,—H. aspersa, H. nemoralis and H. 
¥. 
op NW bO 
3 3, Mouth with an internal band .. 
No internal band ; minutely umbilicated 
