| 1. Gazelle. 3. Gazelle (of Sœmmering). | 2. Antelope (Oryx-leucoryx). 4. Nanguer. |
In the deserts of Africa and Arabia the traveller frequently meets with small rodents, which excavate their burrows in the sandy soil, and only issue from them at night in quest of food. These are the jerboas and jerbilles. The jerboas are easily recognized by the length of their hind-legs and the disposition of their toes—three to each hind-foot, the middle larger than the rest; five to each fore-foot; and all furnished with sharp, strong, crooked claws; their structure resembling that of the raptores among birds. These animals leap with great celerity, and to an extraordinary distance. The tail, which is a fifth longer than the body, and terminated by a tuft of black hair, forms at one and the same time a sort of balance, a rudder, and a lever. It enables the jerboa to preserve his equilibrium, and to direct himself when he has taken his spring; or, in a state of repose, furnishes him with a substantial support.
The jerboas constitute, in the family of dipodidæ, a tribe composed of several species, which are found in eastern and central Europe, Asia, and Africa.
The jerbilles, owing to the similarity of name, are often confounded with the jerboas; but the only things they have in common are a certain conformity of habits, and a nearly equal aptitude for leaping.
Otherwise, their organization rather resembles that of the rat, along with which it is classed by zoologists. Their hind-legs are much shorter than those of the jerboa, and their tail is garnished with but a few short, stiff hairs. Like the jerboas, they inhabit the sandy wildernesses of Africa, Asia, and eastern Europe.
These small animals, exclusively frugivorous and graminivorous, seem able, in the solitary places where they make their retreats, to multiply themselves ad infinitum; but, while a great number perish through famine, they are also decimated by a host of enemies in the reptiles of the Desert, and especially by the terrible horned viper, or cerastes, and a great saurian, intermediate between the lizard and crocodile—the “varan of the Desert.”