CEPIIALO'PODA, Maiducia of Aristotle, Mollia of Pliny, Ceplat lophora of De Blainville, Antliolyraeltiophora of Gray, a class of Mollusks whose mantle, according to Cuvier, unites beneath the body, and thus forms a muscular sac which envelops all the viscera. This body or trunk is fleshy and soft, varying in form, being either sub spherical, sub-plano-elliptical, or elongate-cylindrical, and the sides of the mantle are in many of the species extended into fleshy fins. The head protrudes from the muscular sac, and is distinct from the body ; it is gifted with all the usual senses; and the eyes in particular, which are either pedunculated or sessile, are large and well developed. The mouth is anterior and terminal, armed with a pair of horny or calca reous mandibles, which bear a strong resemblance to the bill of a parrot, acting vertically one upon the other. Its situation 1;3 the bottom of a subconical cavity formed by the base of the numerous fleshy tentacular appendages which surround it, and which have been termed arms by some naturalists and feet by others.
These appendages in the great majority of living species are provided with acetabula—suckers or cupping-glass-like instruments—by means of which the animal moves at the bottom of the sea, head downwards, or attaches itself to its prey or to foreign bodies. These suckers are either unarmed or armed with a long sharp horny claw, as in Onychoteuthio. In the unarmed acetabulum the mechanism for adhesion is so perfect during life that, as Dr. Beget well observes in his Bridgewater Treatise,' "while the muscular fibres continue contracted it is easier to tear away the substance of the limb than to release it from its attachment ; and even in the dead animal the suckers retain a considerable power of adhesion." The same author clearly describes the apparatus by means of which the acetabulum executes its functions :—" The circumference of the disc is raised by a soft and tumid margin ; a series of long slender folds of membrane, covering corresponding fasciculi of muscular fibres, con verge from the circumference towards the centre of the sucker, at a short distance from which they leave a circular aperture ; this opens into a cavity which widens as it descends, and contains a cone of soft substance rising from the bottom of the cavity, like the piston of a syringe. When the sucker is applied to a surface for the purpose of adhesion, the piston, having previously been raised so as to fill the cavity, is retracted, and a vacuum produced, which may be still further increased by the retraction of the plicated central portion of the disc.
Here we have an excellent description of the apparatus for holding on,' but the explanation stops short of showing how the operation of 'letting go' in effected. We well remember In our youth going far out with an old fisherman of Dawlish to visit his floating nets which he had laid for the pilchards. As we looked down into the clear blue water we could see that the number of fish entangled was great ; but to the great discomfiture of the fisherman, who was eloquent on the occasion, almost every other fish was locked in the embraces of a cuttlefish plying his parrot-like mandibles to some purpose. The fisherman who seemed to regard these unbidden guests as an incarnation of all evil, carried a capacious landing-not, but so quick wns the eight 'of these C.ephalopo6, so ready were they in letting go and agile in darting back or sideways clear of the net, that though the greedy creatures held on to the List moment, the fisherman did not secure above three out of the crowds that had spoiled his haul. Upon mentioning this to Mr. Owen, ho informed us that the muscular arrangement enabled the animal, when it was disposed to let go its hold, to push forward the piston, and thus in a moment destroy the vacuum which its retraction had produced." The same author Cycloptedia of Anatomy and Physiology,' article ‘Cephalopoda) has stated that in the Calamary the base of the piston is inclosed by a 1 horny hoop, the outer and anterior margin of which is developed into a series of sharp-pointed curved teeth. These can be firmly pressed into the flesh of a struggling prey by the contraction of the surrounding transverse fibres, and can be withdrawn by the action of the retractile fibres of the piston. Digestive Organs.— e tongue, which is beset with horny points, lies between the mandibles, and the oesophagus widens into a kind of crop which leads to a gizzard nearly as fleshy as that of birds. To the gizzard succeeds a third stomach, which is membranous and somewhat spiral, wherein the liver, which is of considerable volume, pours the bile. The rectum opens into the infundibulum.