CHAPTER X.

Functions and Instincts. Cephalopods.

We have now taken leave of what may be called the proper Molluscans, including the Bivalves, and Univalves1 of Aristotle and Linné, or the Conchifers and Molluscans of Lamarck, and are arrived at a Class remarkable, not only for their organization, form and habits, but also for their position in the animal kingdom; for in their composition they seem to include elements from both the great divisions of that kingdom: from the Vertebrates-the beak, the eye, the tongue, an organ for hearing, the crop, the gizzard, and an analogue of the spine, with several other parts enumerated by Cuvier; and from their own sub-kingdom, many of their remaining organs. We may descend to the very basis of the animal kingdom for the first draught of their nervous system, for it is discoverable in the wheel-animals in which Ehrenberg detected pharyngal ganglions and a nuchal nervous collar; the sucker-bearing arms seem to have their first outline in the fresh water polypes ;3 indeed if the mouth of the cuttle-fish with its suckers, be separated from the head, leaving behind the long arms, we see immediately an analogue of a radiary, particularly of a star-fish, with its rays bearing suckers below, and its central mouth. The lamellated tentacles observed by Mr. Owen in his work, before quoted, on the animal of the Pearly Nautilus, above and below the eyes, seem to lead to the antennæ of Crustaceans and Insects, and numerous Molluscan characters are obvious to every one. From these circumstances it seems evident that the Creator has placed this tribe in a station which leads to very different and distant points in the animal kingdom, and that their is scarcely any but what may recognise in it one or more of its own peculiar features-yet at the same time it exhibits many characters, both in its most extraordinary outward form and its internal organization, that are quite

1 Διθυρα. Μονοθυρα.

2 Ganglia nervea pharyngea. Annulus nerveus nuchalis. Ehren. 3 Hydra.

4 Nautilus Pompilius.

peculiar and sui generis, of which no animal at present known exhibits the slightest traces. To mention only its muscular apparatus adapted to its unparalleled form; its system of circulation, carried on in the first Order by three distinct organs instead of one heart; and the wonderful complication of their tentacles, of the nerves that move them, and the vascular system that animates them.

This singular Class, which Cuvier denominated Cephalopods, or having their feet attached to their head, appears to follow very naturally the Trachelipods and Heteropods, lately described, which have not only eyes furnished with iris, and pupil, but also distinct sexes, and are of predaccous habits, all characters which they possess in common with the Cephalopods or Cuttle-fish. There is, however, an animal amongst the naked Gastropods-called by the ancients, from its tentacles representing the ears of a hare, the sea-hare,' a name it still bears in Italy, which Linné named Laplysia, in which he was followed by Lamarck, but modern writers after Gmelin have called it Aplysia, a name used by Aristotle for a very different animal, a kind of sponge, and, therefore, improperly applied-this animal has many characters that are found in some of the Cephalopods, particularly in its circulating and nervous systems; in having internal solid parts, and in discolouring the water with an inky fluid, so that there seems also a connexion between this genus, and the Cephalopods, amounting to something more than a mere analogical resemblance.

Mr. Owen has divided this Class into two Orders, from the composition of their respiratory organs, namely, those that have two branchiæ,3 or gills, and those that have four. The first includes those that have no shell, and the second those that have one. The last is farther divisible into those whose shell has many chambers, as the Nautilus, and those where it has only one, as the Argonaut, or paper nautilus.

To the first of these Orders belongs the Cuttle-fish," one of the most wonderful works of the Creator. Its mouth is surrounded by eight long fleshy arms, or rather legs, somewhat conical in shape, and acute at the end, moved by innumerable nerves, furnished from numerous ganglions: these legs can bend in every direction with the utmost vigour and activity, their surface is furnished with many suckers, by which they can fix themselves strongly to any thing they wish to lay hold

1 Lepus marinus, Plin. 3 Dibranchiata.

2 Hist. An. 1. v. c. 16. 4 Tetrabranchiata,

5 Sepia.

2

of, and by means of which, like the star-fish,' they can move from place to place. When this animal walks, in this resembling also the star-fish and sea-urchin, it moves with its head and mouth downwards and its body elevated. It swims also and seizes its prey by means of these organs: besides these arms or legs, for they perform the functions of both, there is a pair of long organs, one on each side, having their origin between the first and second pair of legs, which are incrassated at the end, where, also, they are furnished with many suckers. Cuvier supposes they use these as anchors to maintain them in their station during tempests, and as prehensile instruments, by which they can seize their prey at a distance. In the centre of the legs is the mouth, surrounded by a tubular membranous lip, including a beak, consisting of two mandibles, like that of a paroquet; these mandibles or jaws are crooked, and the upper one fits into the lower as a sliding lid into a box. With these redoubtable jaws the cuttle-fish devours fishes, crustaceans and even shell-fish, which receive a farther trituration in its muscular crop and its gizzard. By means of the suckers on their legs and arms, they lay such fast hold of their prey as to deprive them of all power of motion; thus they master individuals much larger than themselves. The hard and often spinose crust of crabs or lobsters cannot withstand the action of their trenchant jaws, and they do not fear the gripe of their claws. Their large eyes, which resemble those of vertebrated animals, by their look of ferocity, are enough to create an alarm in the animals they pursue, and are said to see in the night as well as the day. So that although they are not like Pontoppidans Kraken the notion of which is thought to have been taken from a large cuttle-fish-half a league in circumference, so as to be mistaken for floating islands, yet they are really as tremendous animals, their size considered, as any that Providence has commissioned to keep within due limits the populace of the waters.

One of their most remarkable and unique features, is the manner in which circulation takes place in them. They have three hearts; the principal one, seated in the middle, sends the blood through the arteries: the blood returns by a vena cava, which, dividing into two branches, carries it to the two lateral. hearts, each of which sends it to the gills for oxygenation, whence it returns again by the intermediate heart.

The Octopus, called by the French writers the Poulpe, probably a contraction of polype, differs from the common cuttle

1 See above, p. 108.

2 lbid. p. 114.

fish, having neither the arms nor long tentacles of that animal, and instead of the large heavy bone has only two small cartilages. This different structure is rendered necessary by the difference in their habits. The body of the octopus is small, and it has legs sometimes a foot and a half in length, with about two hundred and forty suckers on each leg, arranged, except near the mouth, in a double series; so that it walks with ease. They are often out of the water, and frequent rough places, are excellent swimmers, and move rapidly in the water with their head behind. The cuttle-fish, whose legs are short and body heavy, prefer the bottom, and do not attempt to swim, for which they are not well fitted. Providence has, therefore, given them their long arms to compensate for the shortness of their legs.

A remarkable peculiarity distinguishes these animals. They are furnished with an organ which secretes a black fluid, with which they can produce an obscurity in the water that surrounds them, on any appearance of danger, or to conceal themselves from their prey. The Chinese are said to use it in making the ink that bears the name of their country; something similar, but not so black, is prepared from it in Italy; and Cuvier used it to colour the plates for his memoir on these animals.

The second order of cephalopods, or at least the pearly nautilus, differs in several respects from those which constitute the first, and which I have just described, approaching much nearer to the Molluscans. The most striking approximation, and which first catches the eye of the examiner, is its shell, which, though its spiral convolutions are not externally visible, exhibits a general resemblance to a univalve shell. To a person who had the opportunity of witnessing the motions of the animal that inhabits it, the first thing that would strike him, would be the means by which it progressed upon the bed of the sea; he would see no motion produced by the action of tentacular legs furnished with suckers, like those of the cuttle-fish, but instead of it, by a single expansive organ, exhibiting considerable resemblance to the foot of a snail. This organ, Mr. Owen, led by the nervous system, regards as surmounting the head and as its principal instrument for locomotion. The oral organs of this animal are much more numerous and compli cated than those of the cuttle-fish, and are furnished with no suckers. Its tentacles are retractile within four processes, cach pierced by twelve canals protruding an equal number of these organs, so that in all there are forty-eight. In fact, the whole oral apparatus, for the full description of which I must

refer the reader to Mr. Owen's excellent tract, except the mandibles and the lip, is formed upon a plan different from that of the cuttle-fish, as likewise from that of the carnivorous trachelipod Molluscans, and indicates very different modes of entrapping and catching their prey.

The eye, also, Mr. Owen states to be reduced to the simplest condition that the organ of vision can assume, without departing altogether from the type of the higher classes, so that it seems not far removed from that of the proper Molluscans. In this animal there is only a single heart, the branchial ones being wanting.

There is one circumstance which proves this cephalopod to belong to this shell, and not to be a parasitic animal as that of the argonaut has been supposed to be-it is this, though the whole body appears to reside in the last and largest concameration of the shell, yet there is a small tubular tail-like process which enters the siphon, but which unfortunately was mutilated, only a small piece being left, but enough to show that the animal had power over the whole shell by means of this organ: hence it follows that a Cephalopod is the animal that forms the shell of the nautilus, and its natural inhabitant, which goes a great way towards settling the controversy concerning the real animal of the argonaut, and amounts almost to a demonstration that the celebrated sailor that uses it as a boat, and scuds gaily in it over the ocean, is no pirate that has murdered its natural owner, but sails in a skiff of his own building.

The only circumstance that now leaves any doubt in the mind of the inquirer, is the very different nature of the cephalopod of the argonaut and the nautilus, the former appearing to be nearly related to the octopus or poulpe, and belonging to the genus Ocythöe of Rafinesque. In this genus the tentacular legs or arms are similar to those of the poulpes, planted on the inner side with a double series of sessile suckers, the second pair having a membranous dilatation at their apex,1 which the animal is supposed to use as a sail when it moves on the surface of the sea. Some naturalists deny that this animal ever uses these organs for sailing or rowing, but Bosc expressly asserts, and I am not aware that there is any reason to doubt his veracity, that he has seen hundreds of the argonauts rowing over the surface of the sea, in calm days, at so small a distance from the vessel in which he was sailing, that though he could not catch one, he could observe all their manœuvres;

1 See Zool. Journ. n. xiii. t. iii.