WATER SNAILS. 
195 
minence of the spire and the outline of the 
mouth. 
This little mollusk is generally distributed 
throughout Britain and Europe, and extends 
into North Africa, Afghanistan, and Siberia. It 
inhabits the banks of ditches, canals, muddy 
streams, and rivers; it is found on the stones 
of pools at considerable elevation on mountains, 
where it is preyed upon by the lapwing; 
it also frequents the moist mud and damp places 
about springs and waterfalls. I have even taken 
it in the rills at the margins of the high roads, 
in which spots it was only occasionally bathed 
in water, during and for a short time after rain. 
L, truncatula , living as it does on the margins 
of streams, pools, &c., differs in its habitats from 
the species of the genus, which invariably pass 
their days on submerged plants. In such spots 
as indicated, this species deposits its eggs, which 
are not fixed to the stems of aquatic plants, as 
are those of its congeners, but are united in little 
rounded masses, which rarely contain more than 
from fifteen to twenty eggs. 
In the heat of summer, the small mud-snails 
bury themselves in the mud. 
Limn^a glaber— (the Smooth Mud Shell) 
(PI. X., fig. 115).—One of its synonyms is L . 
octona , or “ the Eight-Whorled Mud Shell.” 
The shell of this species is elongated, tapering, 
o 2 
