124 LAND AND FEESH-WATER MOLLUSKS. 
vegetation on downs and heaths. It is generally 
found in greater abundance on the sea-coast, but 
occurs in many inland districts. It is a very 
abundant and gregarious species, adhering in 
clusters to the stems of various plants. During 
the hot weather they bury themselves about the 
roots of plants; but after a shower of rain they 
appear in such abundance that they are supposed 
by country folks to come down from the clouds 
with the rain. 
Helix virgata has the propensity of feeding upon 
Goccinella and other small insects, and is itself, 
with its congeners, accidentally eaten by sheep 
pasturing on the downs and commons, where it 
occurs in such profusion. “For it is indeed im¬ 
possible that the sheep can browse on the short 
grass without devouring a prodigious quantity of 
them, especially in the night, or after rain, when 
they ascend the stunted blades;^ and in the South 
of England it is a prevalent, and probably a 
correct opinion, that these snails contribute much 
to the fattening of sheep. The superiority of the 
Dartmoor and Southdown mutton is presumed 
to be attributable to the flavour imparted to it by 
these mollusks. The distoma , or fluke of sheep, 
possibly may be derived from the embryonic 
form which lives parasitically in the snail. 
Some authors have remarked, from their own 
observations, in particular localities, that it is 
