CLASS FIRST. 
MOLLUSCA. 
The animals which inhabit shells of this class are soft, 
without articulations of any kind. They are provided with 
a head, which is furnished with tentacula, or having arms 
which are disposed in the form of a coronet. Almost al} 
the species have eyes, and a mouth which is either elon- 
gated, short, or tubular ; usually extensile, and armed with 
hard processes for the mastication of food. The body is 
generally partly invested with a process called a mantle, 
with free edges on the sides of the body. In some instances, 
the body is destitute of any shelly covering, and frequently 
enveloping an internal, simple, testacious plate. 
ORDER I.— HETEROPODA. 
No shells of this order have been found in a fossil state, 
ORDER II.— CEPHALOPODA. 
The head of the animal projecting from a sack-shaped 
body, and provided with a series of inarticulated arms, each 
of which are furnished with suckers. 
GRAND DIVISION I.—CEPHALOPODA SEPIARIA. 
This includes the cutile fish, which are destitute of a shelly 
covering. 
GRAND DIVISION Il. —CEPHALOPODA MONOTHALAMA. 
Shell unilocular, entirely external, and enveloping the ani- 
mal, 
