A MANUAL 
OF THE 
LAND AND FRESH-WATER MOLLESCA 
OF 
THE BRITISH ISLANDS. 
Mollusc A is the name given to that large division 
of the animal kingdom which is characterised by 
having a soft fleshy body, destitute both of a bony 
skeleton supporting jointed limbs, and of a hard 
ringed skin. 
They are covered with a muscular coat, called a 
mantle^ endued with a glairy humour, and are gene- 
rally furnished with a calcareous envelope called a 
shelly which is secreted by this coat for the protec- 
tion of the body or of the more vital organs of the 
animal. 
They are usually elongate, walking on a single 
central foot or disk, and are furnished with one or 
more pairs of organs on the head and sides. Their 
nervous system, which affords the most distinctive 
character of the larger groups of the animal king- 
dom, merely consists of a certain number of medul 
B 
