Family III. Trionychidæ.
(Soft Tortoises.)
These are large Tortoises which have no horny shell, but the carapace and plastron are covered with a soft skin. The ribs do not reach to the border of the carapace, nor are they united through the whole of their length, the parts analogous to sternal ribs being replaced by a simple cartilage; and the sternal pieces are partly dentelated as in the Turtles, and do not cover the whole inferior surface. The feet, like those of the preceding family, are webbed, but not lengthened; only three toes of each foot are furnished with nails. The horny beak is covered on the outside with fleshy lips, and the muzzle is produced into a short trunk. The tail is short, and the anal orifice of the body is situated near its extremity.
The Soft Tortoises inhabit great rivers and lakes, where they live upon aquatic animals; they are eminently carnivorous and voracious, and pursue with agility in the water, fishes, and especially young crocodiles. Notwithstanding the nature of their food, their flesh is esteemed for the table, and hence they are caught with a hook and line: it is necessary, however, as MM. Duméril and Bibron assert, that the hook should be baited with a living prey, or at least that the motion of apparent life should be communicated to it, if dead, as they are said never to touch a dead or immoveable prey. This does not apply, however, to the eggs of Crocodiles, which the
