It lived for more than three years, and might have grown to a much larger size, but for the neglect of an attendant who forgot on one winter night to keep up the fire which warmed the water, and in consequence this interesting creature was found dead next morning.
Here then we have a carnivorous being of more than ordinary voracity, and requiring a constant supply of fish. But, during the rainless summer, the water is rapidly evaporated under the sun’s rays, the fish die, and the muddy bed of the river becomes as dry and nearly as hard as brick. What then is the Lepidosiren to do?
By Divine Providence, the heat which withdraws its food acts upon it as cold acts upon hibernating animals in this country. As soon as the drying-up process has begun, the Lepidosiren wriggles itself into the mud while it is still soft, and by dint of turning round and round, makes a sort of chamber, the sides of which are preserved from collapsing by the slime which it pours from its body.
It then doubles itself up sideways in a most curious fashion, wrapping the membranous tail over its head so as to cover it entirely. The body is not coiled in a circle, as might be imagined, but the two inner sides (mostly the left) are pressed closely against each other, so that the animal occupies a wonderfully small space. The dimensions of the chamber are soon contracted by the weight of the superincumbent mud, until at last there is scarcely the eighth of an inch of free space round the body.
In this curious refuge the Lepidosiren passes into a state of Estivation. The mud is gradually dried, and then baked under the fierce rays of a tropical sun. But the Lepidosiren lies motionless and unconscious until the next rainy season refills the river, dissolves the hardened mud, and sets the creature free to resume its predatory life.
Were it not for the Lepidosiren, the inhabitants of these countries would often be hardly pressed for food. But they search the dry bed of the river, dig up the buried estivators and live on them. So here we have Estivation as well as hibernation, indirectly beneficial to man. I may mention that most of the Lepidosirens which have been kept alive in this country were brought while still buried in their mud cells.
There is little difficulty in finding the hidden Lepidosirens, as the aperture through which they entered the mud seems almost invariably to remain open, its smooth and slime-polished sides leaving no doubt as to its identity.
I have possessed for more than four years a large lump of dry Nile mud, a hole in one of its sides showing that a Lepidosiren ought to be inside it. This morning I carefully cut it open, and there found the inhabitant, doubled up, with its tail over its head just as when it gave itself up to slumber more than twenty years ago. I expected to have seen a nearly spherical chamber, but found that the cell is cylindrical, and only just large enough to hold the creature.
The slime with which the cell is lined has been hardened into a papery consistence, and is, in fact, about as thick as the paper on which this account is printed. When a piece is torn off and held in the flame of a spirit lamp, it takes fire and it gives out a very nauseous odor, like that of a beetle’s wing case when similarly burned. This thick coating of slime is only to be found in the cell itself, and surrounding the body of the animal. I imagine that the Lepidosiren must deposit many successive coats of slime after it has taken up its position. These cells are technically named “cocoons.”
As some time elapses between the falling of the rain, when the creature awakes, and the dissolving of the cocoon, there must be some peculiar structure of the respiratory organs. Otherwise, the Lepidosiren, being a fish, and breathing by gills, must die before it can reënter the water.