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Show 6 S'l'. JAGO-·CAPE DE VERD ISLANDS. Jan. 1832. senes : the height of the cliff thus affording a rude measure of the age. . During our stay, I observed the habits of s.ome man~e animals. A large Aplysia is very common. Th1s sea-slug IS about five inches long; and is of a dirty yellowish colour, veined with purple. At the anterior extremity, it has two pair of feelers ; the upper ones of which resemble in shape the ears of a quadruped. On each side of the lower surface, or foot, there is a broad membrane, which appears sometimes to act as a ventilator, in causing a current of water to flow over the dorsal branchire. It feeds on delicate sea-weeds, which .grow among the stones in muddy and shallow water; and I found in its stomach several small pebbles, as in the gizzards of birds. This slug, when disturbed, emits a very fine purplish-red fluid, which stains the water for the space of a foot around. Besides this means of defence, an acrid secretion, which is spread over its body, causes a sharp, stinging sensation, similar to that produced by the Physalia, or Portuguese man-of-war. I was much interested,; on several occasions, by watching the habits of an Octopus or cuttle-fish. Although common in the pools of water left by the retiring tide, these animals were not easily caught. By means of their long arms and suckers, they could drag their bodies into very narrow crevices ; and when thus fixed, it required great force to remove them. At other times they darted tail first, with the rapidity of an arrow, from one side of the pool to the other, at the same instant discolouring the water with a dark chestnutbrown ink. These animals also escape detection by a very extraordinary, chameleon-like, power of changing their colour. They appear to vary the tints, according to the nature of the ground over which they pass: when in deep water, their general shade was brownish purple, but when placed on the land, or in shallow water, this dark tint changed into one of a yellowish green. The colour, examined more carefully, was a French gray, with• numerous minute spots of bright yellow : the former of these varied in intensity ; the latter Jan. 1832. HABI'l'S OF 0C'I'01"US. 7 entirely disappeared and appeared again by turns. These ~ha~ges were effected in such a manner, that clouds, varying m tl~t between a hyacinth red and a chestnut brown,* were ~ontmually ~assing over the body. Any part being subJect_ ed. to a slight shock of galvanism, became almost black: a s1m1l~r effect, but in a less degree, was produced by scratchmg the skin with a needle. These clouds, or blushes, as they may be called, when examined under a glass are describe~ as bein? produced by the alternate expansions' and co~tractwns of mmute vesicles, containing variously-coloured flmds.t ~his cuttle-fish displayed its chameleon-like power both durmg the act of swimming and whilst remaining stationary at the botto~. I was much amused by the various arts to escape detectwn used ~y o~e individual, which seemed fully awar: that I was watchmg It. Remaining for a time motionless, It would then stealthily advance an inch or two, like a cat after a mouse; sometimes changing its colour : it thus pro~eeded, till havi~g gai~ed a deeper part, it darted away, ~eavmg a dusky tram of mk to hide the hole into which It had crawled. While looking for marine animals, with my head about two feet above the rocky shore, I was more than once sal_uted by a jet ~f water, accompanied by a slight grating nmse. At first I d1d not know what it was, but afterwards I ~ound out that it was the cuttle-fish, which, though concealed m a hole, thus often ~ed _me to its discovery. That it possesses the power of eJectmg water there is 110 doubt and it appeared. to ~e certain that it could, moreover, take good a1m by d1rectmg the tube or siphon on the under side of its bo_dy. From the difficulty which these animals have in carrymg their heads, they cannot crawl with ease when placed on _the gro~nd. I observed that one which I kept in the cabm was slightly phosphorescent in the dark. ST. PAuf's RocKs.-In crossing the Atlantic we hove to ' • So named according to Pat. Symes's nomenclature. t See Encyclo. of Anat. and Physiol., article Cephalopoda. |