selves in the mouth of an obliging neighbour, and to take their tithes of the succulent morsels which he swallows. This little fish has received the name of Stegophilus insidiatus. We see that in the animal world it is not always the great which take advantage of the little. Still, let us not be deceived; there are fishes in the latitude of the Island of Ceylon which really hatch their eggs in the cavity of the mouth, and we have seen some in the museum at Edinburgh, labelled with the name of Arius bookei. Louis Agassiz has made the same observation on a fish of the Amazon, which has also been recognised by Jeffreys Wyman. One fish wraps up its eggs in the fringes of its branchiæ, and protects them till they are hatched; another lays its eggs in holes hollowed out by itself in the steep banks of the river, and protects the young ones after they are hatched.

To hatch the eggs in the mouth is not more extraordinary than to hatch them in any other part of the body. The Sygnathidae hatch theirs in a pouch behind the anus; and it is a curious circumstance that the females do not undertake this duty. The males alone carry their progeny with them. This recalls to our recollection that curious example of the birds known under the name of Phalaropes, among which the males only hatch the eggs. The female of the cuckoo abandons her eggs, and entrusts them to the female of another bird.

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 medusa; 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.

The pilot has sometimes been confounded with a very different fish, which does not merely remain in the neighbourhood of the shark, but establishes itself upon him, and moors himself to him by the aid of a particular apparatus, for a longer or shorter time; we may even say during the whole of the voyage. This is the Remora.

Is this fish the messmate of the shark to which he is attached? As in the case of the pilot, an examination alone could decide the question. We have opened at the British Museum the stomachs of several remoras of different sizes, and we have been able to ascertain that they also fish on their own account; their food was

composed of morsels of fish which had served as bait, of young fish swallowed whole, and of some remains of crustacea. The remora is simply anchored to his host, and asks from him nothing but his passage. He is contented, like the pilot, to fish in the same waters as the shark which transports him. Sailors, even now, are convinced that if any one of these remoras should attach itself to the ship, no human power could cause it to advance, and that it must of necessity stop. It is certain that the fishermen of the Mozambique Channel take advantage of this faculty, to fish for turtles and certain large fish. They pass through the tail of the remora a ring to which a cord is attached, and then send it in pursuit of the first passer-by which they consider worthy to be caught. This kind of fishing resembles in some degree the sport of hawking with falcons.

So extraordinary a being could not fail to attract the attention of those among the ancients who were students of nature. Pliny assures us that the remora was used in the preparation of a philtre capable of extinguishing the flames of love.

There must be many free animal messmates among insects, and entomologists should make them known; for example, many of them live with ants, as the Pselaphide and Staphylinidæ. Certain hairs of these insects, it is said, secrete a sweet liquid of which ants partake greedily. If we may believe a skilful observer, Mons. Lespès, there are some among them, as the Clavigers, which in exchange for the services which they render are fed by the ants themselves. We may also mention the larvæ of the Meloë, which seem to live as parasites, and the true nature of which was so long unknown.