Because most of them are covered with a firm long-shell, the upper part of which is connected with the spine and ribs, and is covered by the broad horny plates, which in many species are so firm, and of such beautiful colours as to be employed for various purposes of art. There are usually thirteen such plates in the middle, and twenty-four round the edges. The under-shell, covering the belly, is somewhat smaller than the upper, with openings for the head, the tail, and the feet.
In a Singapore newspaper we read, that the tortoise, when caught by the Eastern islanders, is suspended over a fire, kindled immediately after its capture, until the effect of the heat loosens the shell, so that it can be removed with the greatest ease. The animal, now stripped and defenceless, is set at liberty. If caught in the ensuing season, or at any subsequent period, it is asserted that the unhappy animal is subjected to a second ordeal of fire, rewarding its captors this time, however, with a very thin shell.
We do not quote this fact for its refinement of cruelty, but to prove the tenacity of life in the tortoise, which must be accounted a very singular fact in natural history.
Blumenbach observes, that the peculiar and distinct form of this consequently isolated genus, forms a very strong proof of the non-existence of the supposed gradation of objects in nature.
Because they are destitute of teeth.
Because they may there be hatched by the heat of the sun. A single nest has been known to furnish 500 eggs.
Because the former leaves its eggs, one by one, as it hobbles over the ground,neither covering nor taking any care of them whatever, nor paying any regard to the offspring. The water turtle, on the contrary, covers its eggs so accurately as to leave no signs perceptible of its nest; and, however strange it may seem, she so arranges it as to make her tract appear unbroken over the sands, and, after laying her eggs, she proceeds on again in the same direction to complete the deception.
Because it feeds solely on sea-weeds. It is named from the pale olive-green colour of the shell, and the still more remarkably green colour of its fat. This species sometimes weighs 800 weight.
Because its high-arched shell is very regularly marked with black and yellow.