THE CUTTLE-FISH. 
113 
protection to the animal while swimming backwards, situated 
as it is on the dorsal side of the body, and within the substance 
of the mantle or pallium. From its position it is termed a 
pallial shell (fig. 2 s). 
The action of breathing is so performed as to have a certain 
resemblance to the respiratory actions in ourselves, as it is 
accompanied by alternate contractions and expansions of the 
body. The mantle is first expanded, and the consequence is 
an inrush of water into the pallial chamber in which lie the 
gills. Then the margin of the mantle is closely applied to the 
body (becoming, as it were, buttoned up by the application of 
three cartilaginous prominences to corresponding depressions) 
and afterwards contracted, driving the water violently out of 
the funnel, which is provided internally with a valve so con- 
structed as to freely allow the egress of water, but to oppose 
its ingress. Locomotion and respiration are thus simulta- 
neously effected, as the stream of water issuing from the funnel 
drives the cuttle-fish in an opposite direction — that is, back- 
wards. This continual contraction and expansion of the mantle 
supplies the gills in the pallial chamber with a continually 
renewed supply of water for respiration. 
The mouth of the cuttle-fish is situated, as before said, in 
the middle of the circle of arms and tentacles, and within its 
lip is a horny beak quite like the beak of a parrot, except that 
the lower jaw, instead of the upper one, is the longer. These 
jaws are moved by powerful muscles, and bite vertically, and 
are altogether very different from the jaws of such a creature 
as the lobster. 
The tongue is a very peculiar organ, and one the presence of 
which characterises many creatures more or less allied to the 
cuttle-fish. It is termed an odontophore (tooth-bearer), and 
consists of an elongated ribbon-like structure (bearing small 
teeth), which plays to and fro, by means of special muscles, 
over a cartilaginous cushion, and acts much as a chain-saw. The 
mouth is moistened by the secretion of salivary glands, and 
there is a sack attached to the stomach which probably 
gives out a similar product. The gullet (which is furnished on 
one side with a crop) leads down into a gizzard-like stomach. 
The liver is much more solid and compact than in the lobster, 
thus approximating to the structure of higher animals. 
The cuttle-fish is provided with another, and a very peculiar 
gland, the secretion of which is of great use in helping it to 
escape its enemies. This is the ink-bag, which opens near the 
arms, and which produces an intensely coloured substance. 
When alarmed, the cuttle-fish suddenly expels some of this 
very dark product, which so colours the surrounding water that 
the animal is enabled to escape under cover of the obscurity so 
