JERBOA, the name of an Arabian and North African jump ing rodent mammal, Jaculus aegyptius, typifying the family Jaculidae, but in a wider sense applied to most of the representa tives of that family, which are distributed over the desert and semi-desert tracts of the Old World, although unknown in Africa south of the Sahara. (For the characteristics of the family see RODEN TIA. ) In the Egyptian jerboa the length of the body is 8 in., and that of the tail, which is long, cylindrical and covered with short hair terminated by a tuft, io in. The five-toed front limbs are extremely short, while the hind pair are six times as long. When about to spring, the jerboa raises its body by means of the hinder ex tremities, and supports itself at the same time upon its tail, while the fore-feet are so closely pressed to the breast as to be scarcely visible. It then leaps into the air and alights upon its
four feet, but instantaneously erecting itself, it makes another spring, and so on in rapid succession. It is a gregarious animal, living in burrows, which it excavates with its nails and teeth in the sandy soil of Egypt and Arabia. In these it remains during the day, emerging at night in search of the herbs on which it feeds. It is exceedingly shy, and this, together with its agility, renders it difficult to capture. The Persian jerboa (Allactaga indica) is also a nocturnal burrowing animal, feeding on grain, which it stores up in underground repositories, closing these when full, and only drawing upon them when the supply of food above ground is exhausted. (See also JUMPING MOUSE. )