the rocks, suddenly sprang upon Mr. Beale's arm, which he had previously bared to the shoulder for the purpose of thrusting it into holes in the rocks after shells, and clung with its suckers to it with great power, endeavouring to get its beak, which Mr. Beale could now see, between the roots of its arms, in a position to bite. Mr. Beale declares that a sensation of horror pervaded his whole frame, when he found that this monstrous animal had fixed itself so firmly on his arm. He describes its cold slimy grasp as extremely sickening; and he loudly called to the captain, who was also searching for shells at some distance, to come and release him from his disgusting assailant. The captain quickly came, and taking Mr. Beale down to the boat, during which time the latter was employed in keeping the beak of the cuttle away from his hand, quickly released him by destroying his tormentor with the boat-knife, when he disengaged it by portions at a time. Mr. Beale states that this Cephalopod must have measured across its expanded arms about four feet, whilst its body was not bigger than a large clenched hand.[2]
In one genus of this Class the action of the suckers is increased by a strong and sharp hook which projects from the centre of each. During action these hooks are plunged into the flesh of the victim, securing a yet firmer hold; added to which the two long arms, which are so endowed, and which are over and above the eight possessed by the Poulpe, are capable of being firmly locked together, and thus can be made "to cooperate in dragging to the mouth such powerful or refractory prey as singly the arms might be unable to subdue."
Most of the species of the Class are destitute of any external covering, but a few are protected by a shell. An immense number of fossil species, however, belonged to the latter division, known by the names of Belemnite, Nummulites, Orbulites, Ammonites, &c. The most important existing species possessing a shell, are te Pearly Nautilus of the tropical seas, and the Paper Nautilus of the Mediterranean. The former of these possesses four gills, a peculiarity which distinguishes it from all its fellows: Professor Owen, therefore, proposes to divide the Class into two Orders; the one including the Pearly Nautilus, called Tetrabranchiata, or four-gilled; the other including the rest of the existing species, named Dibranchiata, or two-gilled.
As the animals belonging to the Molluscous Division are very numerous, I propose to limit this volume to those families which are represented by species existing in and around the British Islands, contenting myself with an occasional slight notice of such foreign kinds as have anything particularly interesting in their history. I shall therefore at once proceed to the second of these Orders.
1 ↑ Penny Cyclop. art. Cephalopoda.
2 ↑ Hist. of the Sperm Whale
ORDER DIBRANCHIATA.
(Two-gilled Cuttles.)
The creatures composing this order approach nearest to the Vertebrate animals of all the Mollusca. They have a distinct brain included in a box of cartilage—the vanishing remains of a bony skull; they have large highly-coloured and complex eyes, protected in some species by eyelids; and ears of simple structure, hollowed in the cartilage of the rudimentary skull. They are remarkable for having three separate and well organized hearts, one for the circulation of the arterial blood through the body, the others for the projection of the venous blood through the two gills.
Any person who has had an opportunity of examining one of these animals in a living state, must have been struck with a very curious phenomenon. Over the whole surface of the body there are coloured spots which are perpetually changing their position and figure, running into each other and separating, playing hither and thither, contracting and dilating, appearing and disappearing, with great velocity and in the most singular manner. On close examination, it appears evident that these changes are owing to a fluid which moves irregularly within the substance of the skin. Even after death the spots continue to play for a considerable time, and that on small portions of the skin cut away from the rest.
The cause of this curious appearance is not yet thoroughly understood. Milne-Edwards, whose opinion is entitled to the highest respect, gives the following explanation of it:—"The skin of these animals is furnished with a number of differently-coloured spots, which alternately appear and disappear, and if a portion is put under a microscope, it may be perceived that these changes depend on the contraction of small vesicles filled with a coloured liquid, which reach from the surface of the skin to a considerable depth. When one of these spots appears, the liquid, corresponding here to the pigment in the other case, is propelled towards the superficial part of the vesicle, and there displays itself; whilst during its disappearance it is forced into the deeper parts by the contraction of this superficial point itself, which then becomes almost invisible."[1]
Family Sepiadæ.
(Cuttles and Squids.)
The lingering rudiment of a vertebrate skeleton in these animals has been already noticed; their body encloses, however, a solid support of quite another nature, which represents the true shell so characteristic of Mollusca generally. Within the substance of the mantle, if we slit it up along the line of the back, we find an oblong cavity, within which lies loose, and unconnected with it a large plate, horny in some species and shelly in others. The pen of the common Squid (Loligo vulgaris) is of the former texture; the substance called cuttle-bone, so often found on sandy beaches, is of the latter; but both are strictly analogous to the shell of the slug, which is also enclosed within the mantle; and both are formed in the same manner, namely, by a deposition of horny or shelly matter in a fluid state from the sides of the containing cavity.
The animals of this Family have ten arms, two of which, greatly longer than the rest, are very slender except near their tips, which are dilated; these extremities alone are furnished with suckers. The other eight arms are short, thick, and furnished throughout their whole length with suckers, forming a double row along their under surface.
The body is generally lengthened, more or less flattened, with the skin dilated on each side so as to form a pair of wings or fins. It is probably by means of the impetus afforded to the body by these expansions, that some species of the Family are enabled to throw themselves out of the water, and to shoot along through the air to a considerable distance with a motion that resembles flight. These are commonly called Flying Squid.
Mr. F. D. Bennett describes a portion of the Northern Pacific as peculiarly animated by the presence of various oceanic creatures. The Albacore, the Sword-fish, the Barracuda, the Bonita, the Flying-fish, are mentioned, and among them the Squid, whose movements closely resembled those of the last-named volatile fish. "During a calm, in lat. 30° N., the Flying-squid appeared in larger flights than we had ever before witnessed; persecuted probably by the Albacore (which select this tranquil time to descend deep in the water, and to rove far from the ship in quest of food) they rose from the sea in large flocks, leaping over its smooth surface, much in the same manner, and to the same height and distance, as the Flying-fish. Many of them were captured by birds during their leaps, and one individual, in making a desperate effort to escape some aquatic pursuer, sprang to a considerable height above the bulwarks of the ship, and fell with violence upon the deck."[2]
Genus Sepia.
(The