By comparing these two descriptions, the first of which is taken from Edwards and Hasselquist, and the second from Gmelin, we shall perceive, that these animals resemble each other as much as possible. The jerboa is only smaller than the alagtaga, and has only four toes on the fore-feet, and three on the hind ones, without any spur; while the other has five on the fore-feet, and three and a spur on those behind; but I am inclined to think this difference is not universal, for Dr. Shaw, who has given a description of the jerboa of Barbary, represents it with this spur, or fourth toe, on the hind-feet; and Mr. Edwards remarks, that he carefully examined two jerboas he saw in England, and that he saw no spur in either of them. Thus this character which would specifically distinguish the jerboa from the alagtaga, not being universal is of no consequence, and rather remarks the identity, than the diversity of the species. Neither is the difference of size any greater proof of their being two different species; possibly Edwards and Hasselquist have only described young jerboas, and M. Gmelin, an old alagtaga. There are only two things which create any doubt in my mind, viz. the difference in the size of their tails, and the variety in the climates they inhabit, for the jerboa is common in Circassia, Egypt, Barbary, and Arabia; and the alagtaga, in Tartary, along the Wolga, and as far as Siberia. It is seldom that the same kind of animal inhabits such different climates; and whenever it does happen the species undergoes great changes; which, we presume, is the case with the jerboa, of which the alagtaga, notwithstanding these differences, seems to be only a variety. These little animals commonly conceal their hands, or fore-feet, among their hair; so that at first they appear to have only hind-feet. When they move from one place to another, they do not walk, that is advance one foot before the other, but jump or bound with the greatest ease, four or five feet at a time; they rest themselves in a kneeling posture, and only sleep in the day. In the night they seek for food, like hares, and like them, feed on grass and all kinds of grain. They are of a gentle nature, but are not to be tamed beyond a certain limit. They burrow like rabbits, and in much less time. They lay up a store of grass towards the end of summer in their habitations, and in which, in cold countries, they remain during the winter.