journey, which seems confirmed by the circumstance that their bodies when taken out of the water, even if wiped dry with a cloth, become instantly moist again. Mr. Campbell, a friend of Dr. Hancock's, resident in Essequibo, once fell in with a drove of these animals, which were so numerous, that the Indians filled several baskets with them.

Another migrating fish was found by thousands in the ponds and all the fresh waters of Carolina, by Bosc; and as these pools are subject to be dry in summer, the Creator has furnished this fish, as well as one of the flying ones,' by means of a membrane which closes its mouth, with the faculty of living out of water, and of travelling by leaps, to discover other pools. Bosc often amused himself with their motions when he had placed them on the ground, and he found that they always direct themselves towards the nearest water, which they could not possibly sce, and which they must have discovered by some internal index; during their migrations they furnish food to numerous birds and reptiles. They belong to a genus of abdominal fishes, and are called swampines. It is evident from this statement that these fishes are both fitted by their Creator, not only to exist, but also move along out of the water, and are directed by the instinct implanted by him, to seek the nearest pool Hydrargyra.

Exocœtus.

that contains that element; thus furnishing a strong proof of what are called compensating contrivances; neither of these fishes have legs, yet the one can walk and the other leap without them, by other means with which the Supreme Intelligence has endowed it. I may here observe that the serrated bone, or first ray of the pectoral fin, by the assistance of which the flathead appears to move, is found in other Siluridans, which leads to a conjecture that these may sometimes also move upon land.

Another fish,' found by Daldorff, in Tranquebar, not only creeps upon the shore, but even climbs the Fan palm2 in pursuit of certain Crustaceans which form its food. The structure of this fish peculiarly fits it for the exercise of this remarkable instinct. Its body is lubricated with slime which facilitates its progress over the bark, and amongst its chinks; its gill-covers are armed with numerous spines, by which, used as hands, it appears to suspend itself; turning its tail to the left, and standing, as it were, on the little spines of its anal fin, it endeavours to push itself upwards by the expansion of its body, closing at the same time its gill-covers, that they may not prevent its progress; then expanding them again it reaches a higher point; thus, and by bending the spiny rays of its dorsal fins to right and left, and fixing them in the bark, it con2 Borassus flabelliformis.

1 Perca scandens.

tinues its journey upwards. The dorsal and anal fins can be folded up and received into a cavity of the body.

How exactly does this structure fit it for this extraordinary instinct. These fins assist it in certain parts of its route, and, when not employed, can be packed up so as not to hinder its progress. The lobes of its gill-covers are so divided and armed as to be employed together, or separately, as hands, for the suspension of the animal, till, by fixing its dorsal and anal fins, it prepares itself to take another step; all showing the Supreme Intelligence and Almighty hand that planned and fabricated its structure, causing so many organs, each in its own way, to assist in promoting a common purpose. The fan palm, in which this animal was taken by Daldorff, grew near the pool inhabited by these fishes. He makes no mention, however, of their object in these terrestrial excursions; but Dr. Virey observes that it is for the sake of small Crustaceans, on which they feed.

I shall name only one more animal that migrates for the great purpose of reproduction, and this is not the least interesting of them; and, though it does not furnish so large a supply of food to the countries it passes through, as the migratory fishes, still it is useful in that respect : the animal I allude to is the land-crab.

Several, indeed, of the crabs forsake the waters

for a time, and return to them to cast their spawn; but the most celebrated of all is that known by the above appellation, and alluded to by Dr. Paley, under the name of the violet crab, and which is called by French the tourlourou.1 These crabs are natives of the West Indies and South America. In May and June, when the rainy season takes place, their instinct impels them to seek the sea, that they may fulfil the great law of their Creator, and cast their spawn.

They descend the mountains, which are their usual abode, in such numbers, that the roads and woods are covered with them. They feel an impulse so to steer their course, that they may travel by the easiest descent, and arrive most readily at the sea, the great object at which they aim. They resemble a vast army marching in battle array, without breaking their ranks, following always a right line; they scale the houses, and surmount every other obstacle that lies in their way. They sometimes even get into the houses, making a noise like that of rats, and when they enter the gardens they commit great devastations, destroying all their produce with their claws. They are said to halt twice every day, and to travel chiefly in the night. Arrived at the sea-shore, they are there reported to bathe three or four different times; when

1 Gecarcinus carnifex.

retiring to the neighbouring plains, or woods, they repose for some time, and then the females return to the water, and commit their eggs to the waves. This business dispatched, they endeavour to regain, in the same order, the country they had left, and by the same route, but only the most vigorous can reach the mountains. The greater part are so weak and lean, that they are forced to stop to recruit their strength in the first country they reach. When arrived again at their habitations, they have a new labour to undergo, for now is the time of their moult. They hide themselves in their subterranean retreats for this purpose, so that not a single one can be seen: they even stop up the mouth of their burrows. Some writers, however, affirm that they change their shells immediately after their oviposition.

The respiration of these land-crabs, for a long time, had puzzled comparative anatomists.They could not explain how animals, breathing by gills, could subsist so long out of the water without these organs becoming useless. M. M. Audouin, however, and Milne Edwards, cleared up the mystery by the discovery of a kind of trough, formed by the folds which line and constitute the parietes of the branchial cavity, and destined to contain and preserve a certain quantity of water proper to moisten the gills. One species' has more than one pocket, or vesicle,

1 Gecarcinus Uca.