MOLLUSCA. 
SYNOPSIS OF THE CLASSES. 
I. CepHALOPoDA. Cuttles. 
Head distinct from the body. Mouth surrounded 
by appendages termed legs, which are furnished on 
their inner aspects with suckers: these legs are used 
for locomotion, as well as for seizing their prey. 
Respiration performed by gills, which are placed in 
a sac, with the other automatic organs. 
II. GasreRopopa. Univalves. 
Head distinct from the body, and for the most part 
furnished with tentacles. Respiration performed 
by gills, which are generally internal. Locomotion 
accomplished by a strong muscular foot, attached to 
the under part of the body. 
III. Concuz. Bivalves. 
Head in no degree distinct from the body. Mouth © 
with lips, which are generally produced into trian- 
gulate lobes. Respiration performed by four double 
striated membranes, situated between the martles. 
Locomotion wanting, or performed by a foot, which 
is attached anteriorly to the abdomen. Body pro- 
tected by a shell on each side. 
IV. Bracuiopropa. 
Head in no degree distinct from the body. Mouth 
surrounded by two long and fleshy arms, ciliated on 
each side. Sespiration performed by leaf-like ap- 
pendages, that are attached to each lobe of the 
mantle. Locomotion none. Body protected by a 
shell on each side. 
V. AScIDIz. 
Head not distinct from the body. Respiration per- 
formed by two reticulated sacs surrounding the au- 
tomatic organs, and covered by the mantle. Loco- 
motion none. 
B 
