74 
of long abstinence from food. The power observed 
in the frog of protruding the stomach through the 
mouth is analogous to a corresponding power and 
mode of action in some of the mollusca. The whole 
intestinal canal in serpents approaches closely to that 
of lampreys *. 
The stomachs of fish are various: generally simple, 
scarcely distinguishable from the cesophagus, and the 
intestine shorter than the body: yet they retain food 
for a long time, and only feed at distant intervals. The 
squalus carcharias, the most voracious of marine mon- 
sters, corresponds with the generality of toothed fishes: 
but the basking shark, squalus maximus, which lives 
chiefly on vegetable food, was found by Mr. Home 
to have two stomachs, the second of which opened 
into the intestine by a narrow pylorus: and in it he 
found pebbles, doubtless taken, as by birds into their 
gizzards, for the purpose of trituration. “ The ceso- 
phagus of the crayfish is generally short, and formed 
by thin membranes: it quickly expands into a large 
membranous stomach, which, particularly at its up- 
per part, and in the region of the pylorus, is sup- 
ported by a peculiar bony frame, consisting of five 
flat bony masses moved by muscles. To these bones 
are attached interiorly three larger and two smaller 
teeth, surrounding the pyloric opening of the sto- 
mach.” “ The same form of organization,” according 
to Cuvier, “ prevails through most of the correspond- 
ing species. In some, however, the stomach is merely 
membranous, and provided with small teeth *.” 
* Carus, vol. li. p. 55. $ Ibid. p. 19, 20. 
