82 
COMPARATIVE ZOOLOGY. 
Fishes to disgorge the indigestible parts of their food, and 
some, as the Carp, send the food back to the pharynx to 
be masticated. The stomach is usually bent, like a si¬ 
phon ; but the intestine is nearly straight, and without 
any marked distinction into small and large. Its append¬ 
ages are a large liver and a rudimentary pancreas. 
In the Amphibians, as the Frogs, the digestive appara¬ 
tus is very similar to that of Fishes; but the two kinds 
of intestines can be more readily 
distinguished. The Reptiles gen¬ 
erally have a long, wide gullet, 
which passes insensibly into the 
stomach, and a short intestine 
(about twice the length of the 
body) very distinctly divided into 
small and large by a constric¬ 
tion. 43 The vegetable - feeding 
Tortoises have a comparatively 
long intestinal tube; and the 
Serpents have a slender stomach, 
but little wider than the rest of 
Fio. 47.—Anatomy of a Cepbaiopod the alimentary canal. 
(diagram): a, tentacles; 6, masti- J 
catory apparatus; c, eye; d, sali- The Stomach of the Crocodile 
vary gland; e, nervous ganglia; • i .i , . . 
/, oesophagus; g, internal shell, or 1S inore Complex than any llltll- 
mentioned. It resembles 
tbat 0f the Cuttle-fish,but offers 
chial chamber ; s,branchial heart ; a Still more Striking analogy to 
t, systemic heart; v, mantle. 53,7 
the gizzard of a Bird, having 
very thick walls, and the muscular fibres radiating pre¬ 
cisely in the same manner, so that, in this respect, the 
Crocodile may be considered the connecting link between 
Reptiles and Birds. 44 In Crocodiles also the duodenum, 
with which the intestine begins, is first distinctly defined. 
Into this part of the intestine the liver and pancreas, or 
sweet-bread, pour their secretions. Furthermore, in the 
