COMPARATIVE ZOOLOGY. 
78 
the Lobster, have a short gullet leading to a large cav¬ 
ity, situated in the front of the animal, which is a giz¬ 
zard, rather than 
stomach, as it has 
thick muscular 
walls armed with 
teeth. A well- 
marked constric¬ 
tion separates this 
organ from the in¬ 
testine. The liver 
is highly devel¬ 
oped ; instead of 
numerous folli¬ 
cles, there is a 
large bilaterally 
symmetrical or¬ 
gan, divided into 
th ree lobes on each 
side, pouring its 
secretion into the 
upper part of the 
intestine, which is 
the true stomach. 
Among Insects, 
there is great vari¬ 
ation in the form 
and length of the 
Pig. 40.—Anatomy of a Caterpillar: g, h, oesophagus; h , . 
i, stomach; k, hepatic vessels; l, m, intestine; q, r, sal- Canal. IneiOllOW- 
ivary glands; p, salivary duct; a, b, c, longitudinal : no . ~ ar ,. a 
tracheal trunks; d, e, air-tubes distributed to the vis- 1IJ fe P^rib Cdll geil- 
cera; /, fat-mass; v, x, y, silk-secretors; z, their ex- grailV be distin- 
cretory ducts, terminating in t, the spinneret, or fu- t * 
suius. guished: gullet, 
crop, gizzard, stomach, and large and small intestines, with 
many glandular appendages. The crop, gizzard, and large 
intestine are sometimes absent, especially in the carnivorous 
