4. The Jacard (Crocodiles sclerops, Schneider) appears to be spread over the whole of tropical America, but is more especially numerous in Brazil, where it attains a very large size, and is found in all the rivers and lakes. Its head is more attenuated than in the alligator of North America ; the sides converging towards the snout, so as to form very nearly an isosceles triangle ; the surface of the bones of the skull has a rough scabrous appearance, as if arising from disease ; the orbits of the eyes are surrounded by large prominent rims of bone, and these are con nected together by an intermediate ridge, giving the whole very much the appearance of a pair of spectacles ; finally, the skull is pierced by two very small holes behind the orbits. The cervical plates are remarkably large ; they are arranged in four transverse bands, of which the first two contain four each, and each of the others two. The transverse bands of the back vary according to age, and it would even seem according to the individual ; they most commonly consist of two rows, with two plates each, four with six, five with eight, two with six, and four with four. The colour of the animal is greenish-brown above, marbled irregularly with different shades of green, and pale greenish-yellow below. This species grows to the size of from 14 to 18 feet in length ; the whole length is from eight to eight and a half times that of the head.
The Jacards, according to Azara, are never known to attack men, or even dogs, in passing the rivers, unless it should happen to be near the place where they have deposited their eggs ; and even then, they are never known to prey upon the body, contenting themselves with the fish and water-fowl which they find so plentiful in their own element.
During the night they are exceedingly active, and always keep in the water, showing only their heads above the surface, but towards the middle of the day they come ashore to enjoy the heat of the sun ; they then sleep profoundly, but always retreat to the water on being disturbed. The eggs are about the size of those of a goose ; they are white, and much sought after by the free Indians, who also eat the flesh of the Jacare itself, though it has a strong musky smell, and scarcely any juice. The female deposits her eggs in the sand in a single layer, and covers them with straw or leaves ; few of them, however, escape the quick eye of the vulture, and even many of the young fall a prey to the full-grown males, which at the period of their first appearance, in the hottest part of summer, are particularly fierce and ravenous, the marshes which they inhabit being then dried up, and their food difficult to obtain. This species appears to have pretty nearly the same range towards the south of the continent, that the alligator, or pike-headed crocodile, has to the north. According to Azara, it is never found beyond 32° of south latitude. Many interesting facts regarding the habits of this species are recorded in the narratives of Prince Maximilian, Spix and Martins, and other Brazilian travellers.