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Cuttlefish

sac, arms, situated, water, eyes, siphon and body

CUTTLEFISH, a common name for the Cephalopods, but originally applied to a member of the genus Sepia. In the United States it is restricted to the octopods (q.v.). The cuttle fish proper, S. officinalis, measures from 6 to 10 inches in length, and its color varies from pale-gray to dark-brown or neutral tints. The body is oval, flattened from above downward, and contained in a tough muscular sac (mantle), which expands along the whole of either mar gin into a narrow fin. The integument consists of a single layer of cells, lying upon connective tissue, in which are embedded "chromatophores,* or cells charged with various colored pigment granules. By expansion of the cell the pigment is diffused,. and by its contraction concentrated, hence the rapid flashes of changing color for which the Cephalopod° as a whole are so remarkable.

The head is broad, with a complex cartilage which protects the central nervous system, and the eyes bright green. The front of the head is occupied entirely by the mouth, and the bases of the arms, of which there are 10, 8 having suckers on the extremity in 4 longitudinal rows. The two remaining arms, known as uten tacles,° occupy the interspaces between the ven tral anus and those next to them. They are twice as long as the others, and can be with drawn into pockets situated beneath the eyes and carried in .this position when not in use. The mouth, situated in the centre of the roots of the arms, is surrounded by a lip with seven prominent angles, which bear small suckers in some species.

On the lower side, between the muscular sac and the body proper which contains the viscera, is a hollow space, the or cavity,' containing the siphon, the intestines, kidneys, genital organs and gills. Respiration is carried on by rhythmic contractions of the man tle, in consequence of which water enters at either side, passes over the gills, and is ex pelled by the siphon; this takes place about 70 times in a minute. On the dorsal side of the animal, immediately beneath the integument, is a closed sac which contains the cuttle-bone.

Speaking generally, this may be said to be of an elongated spoon or boat shape; it consists of a horny lamina. Lying parallel to the terminal portion of the intestine is the aink-bag,° a hol low gland opening near the anus, and furnishing a deep-brown fluid, which is ejected by the ani mal when alarmed in order to conceal its retreat. The pigment known as is prepared from it. The heart is situated posteriorly, and con sists of a pear-shaped sac which receives on either side a vein from the gills, dilated just before its termination into a muscular contrac tile antechamber or auricle.

The nervous system consists of the three pairs of ganglia common to the mollusks, concen trated round the cesophagus.

Of the sense organs the eyes are the most conspicuous. They occupy depressions in the head cartilage.

The ears are a pair of small closed vesicles, embedded in the head-cartilage, and supplied by nerves which, though apparently springing from the pedal really have their origin in the cerebral. A ciliated pit, usually consid ered olfactory, lies behind each eye. The sexes are separate. The testis and ovary are both single and situated in the hinder part of the body; the latter lies in the visceral sac or pericardium above described, the former in an almost closed diverticulum of it. The eggs have a tough capsule, with a projection at one end and a kind of handle at the other by which they are attached in bunches to a twig of sea weed or other similar substance.

Cuttlefish are found in littoral regions or in moderately deep water; ordinarily they rest horizontally on or near the bottom, the fins gently undulating, the tentacles retracted, and the arms depressed. Progression may take place by means of the fins with considerable rapidity in either direction, the funnel being turned so that the stream of water issuing from it assists in propulsion; rapid darts backward when the animal is alarmed are brought about either by the sudden ejection of water through the siphon, or by spreading out and reuniting the arms. See CEPHALOPODA ; SQUID.