The cuckoo suggests to us the mound-making Megapode and the Talegalla of Latham, both of which inhabit Australia; these birds deposit their eggs in an enormous mass of leaves or grass, which grows warm by decomposition, and the temperature of which is great enough to hatch them. The young ones when they come
out of the egg are sufficiently developed to be able to provide for their own wants, and to do without a mother’s care.
To return to our animal messmates: let us notice the result of the observations of a learned and skilful naturalist who has rendered great services to ichthyology. Dr. Bleeker has described a still more remarkable association in the Indian seas; it is that of a crustacean, the Cymothoa, taking advantage of a fish known under the name of Stromatea; too imperfectly organized to fish for itself at large, but more skilful in snapping up all that comes within its reach, it makes its home in the buccal cavity of the Stromatea.
But of all crustaceans, the most cruel is the isopod named Ichthyoxena, which hollows out for itself and its female a large dwelling-place in the coats of the stomach of a cyprinoid fish. We will return again to these examples.
The Physaliæ, those charming living nosegays of the tropical regions, also give lodging in their cavities, and in the midst of their long cirrhi, to little adult and perfect fishes, belonging to the family of the Scombridæ, a family to which are attached the tunny and the mackerel. These sea-butterflies flutter away their indolent existence at the expense of their host. Voyagers tell us that they have seen them by dozens concealed in these animated festoons. Mons. Al. Agassiz has mentioned, in his illustrated catalogue, another fact, quite as extraordinary, observed in the Bay of Nantucket, in the United States; it relates to a nocturnal Pelagia (Dactylometra quinquecirra, Ag.) always accompanied, not to say escorted, by a species of herring. The two neighbours constitute
together an association which probably redounds to the advantage of both.
Without quitting our own sea-coast, we find an association of the same kind between young fishes (Caranx trachurus) and a beautiful medusa (Chrysaora isocela). This sea nettle often encloses several young specimens of Caranx, which we are surprised to see issuing full of life from the transparent bodies of these polyps. Indeed, it is not rare to find other fishes in the medusæ. Dr. Gunther, who has arranged with so much care the rich collection of fishes in the British Museum, has shown us some specimens of the Labrax lupus, and of the Gasterosteus, which had been obtained from the interior of different medusæ; and these associations have been also remarked by various distinguished observers, among whom we may mention Messrs. Sars, Rud. Leuckart, and Peach. The captain of the frigate Jouan, when in the Indian Sea, on October 26th, 1871, in 13° 20′ N. lat., and 60° 30′ E. long., that is to say, about 200 leagues to the west of the Laccadive Islands, saw, in very fine weather, the sea, which was at that time very calm, covered with medusæ, and the greater part of these were escorted by many little fishes of the genus Ostracion, the species of which he was unable to ascertain. It is probable that the school of medusæ set in motion certain animals which are eagerly sought after by the Ostracions.
The Pilot is a fish of which much has been recorded; fishing for it is one of the principal recreations of sailors during their long voyages. Some assure us that it snaps off the bait, without touching the murderous hook which threatens the shark; and as it never quits its companion, others have supposed that it lives on the
morsels abandoned by it. Neither of these suppositions is correct; and as the shark does not need its services to point out the danger, we must content ourselves with mentioning this curious association without endeavouring to explain it.
In fact, we have had the opportunity of examining many well-preserved specimens, the stomach of which contained potato parings, the carapaces of crustaceans, the débris of fishes, marine plants (fuci), and a piece of cut fish, which had evidently served as a bait. The pilot does not, therefore, live on the leavings of his companion, but on his own industry, and doubtless finds some advantage in piloting his neighbour. Through the great kindness of Dr. Gunther we have been able to make this interesting examination in the rich galleries of the British Museum. We desire to take this opportunity of expressing our gratitude to this learned man and to his illustrious colleagues, who have the direction of that vast establishment, which is ever open to those who labour for the advancement of science.