MOLLUSCA. 159 
Grnus Prronta.—The body is destitute of the external 
protection of a shell. The head is furnished with two long 
retractile tentacula. The snout is divided into two broad ap- 
pendages. Between the tentacula, towards the right side, is 
the opening forthe penis. The anusis terminal, immediately 
above which is the entrance to the pulmonary cavity; and on 
the right is the opening to the female organs, from which a 
groove runs towards the right lobe of the snout. The mouth 
is destitute of a proboscis or jaws. The tongue is merely 
a cartilaginous plate grooved transversely. The gullet is 
long in proportion, with a villous surface. There are three 
stomachs, each distinguished by its peculiar characters. 
The first is a true gizzard, covered internally with a carti- 
laginous cuticle, and its walls formed of two strong muscles, 
with connecting ligaments. The second stomach is funnel- 
shaped, with prominent ridges both on its external and internal 
surface. These ridges, at their origin internally, are high- 
est, and project considerably into the cavity, acting like a 
valve in retarding the progress of the food. The third 
stomach is short and cylindrical, covered internally with 
equal longitudinal fine ridges. The intestine is nearly of 
equal thickness throughout, and upwards of twice the length 
of the body. The salivary glands are much branched, and 
pour their contents into the entrance of the gullet. The 
liver, in the animals of this genus, is distributed into three 
separate portions, each of which may be regarded as a dis- 
tinct liver, an arrangement which is not known to take place. 
in any other animal. The first liver is situate near the mid- 
dle of the body, on the right side; while the second is 
placed near the posterior extremity. The ducts enter the 
cardiac opening of the stomach, each by a separate aperture, 
and seem to occupy the place of the zone of gastric glands 
