6 CLASS CEPHALOPODA. 
prehension, swimming, and walking. They swim with the 
head backwards, and crawl in all directions with the head 
beneath and the body above. 
A fleshy funnel, placed at the opening of the sac, before the 
neck, affords a passage to the excretions. 
The cephalopoda have two branchiz within the sac, one on 
each side, resembling a highly complicated fern leaf; the great 
vena cava, having arrived between them, divides into two 
branches, which pour their contents into two fleshy ventri- 
cles, each of which is placed at the base of the gill on its 
own side, and propels the blood into it. 
The two branchial veins communicate with a third ventri- 
cle, situated near the bottom of the sac, which, by means of 
various arteries, distributes the blood to every part of the 
body. : 
Respiration is effected by the water which flows into the 
sac, and issues through the funnel. It appears that it can 
even penetrate into two cavities of the peritoneum, traversed 
by the vena cava in their passage to the branchie, and act 
upon the venous blood by means of a glandular apparatus 
attached to those veins. 
Between the base of the feet we find the mouth, armed with 
two stout horny jaws, resembling the beak of a parrot. 
Between the jaws is a tongue, bristling with horny points; 
the cesophagus swells into a crop, and then communicates 
with a gizzard as fleshy as that of a bird, to which succeeds a 
third membranous and spiral stomach, which receives the bile 
from the two ducts of the very large liver. The intestine is 
simple and short ; the rectum terminates in the funnel. 
These animals are remarkable for a peculiar and intensely 
black excretion, with which they darken the surrounding 
water when they wish to conceal themselves. It is produced 
by a gland, and held in reserve by a sac, variously situated, 
according to the species. 
