see Mus, Encycl. where descriptions are given of the jaculus or common jerboa, and of the Arabian, Egyptian, and Siberian jerboas. A variety of this animal has lately been found in Canada by Major-general Davies, F. R. S. and L. S., who says it belongs to Schreber's genus of Dipus, and may be thus characterized: Dipus Canadensis palmis tetradactylis, plantis pentadactylis, caudis annulatis undique fuscis, corpore longior. The truth, however, seems to be, that it is only a variety, if indeed a variety, of the Siberian jerboa. The beautiful figure indeed given by General Davies of the Canadian jerboa differs in some respects from our figure of the Sibericus. Its ears lie flat and farther down the neck; its belly is not so large; its toes are longer; and it has no brush at the end of the tail; but the habits of the two animals seem to be the same. This will be apparent from the following extracts of the General's letter to the Linnean Society:

"The first I was so fortunate to catch was taken in a large field near the falls of Montmorenci, and by its having strayed too far from the skirts of the wood, allowed myself, with the assistance of three other gentlemen, to surround it, and after an hour's hard chase to get it unhurt, though not before it was thoroughly fatigued; which might in a great measure accelerate its death.

"During the time the animal remained in its usual vigour, its agility was incredible for so small a creature. It always took progressive leaps of from three to four, and sometimes of five yards, although seldom above 12 or 14 inches from the surface of the grass; but I have frequently observed others in shrubby places and in the woods, amongst plants, where they chiefly reside, leap considerably higher. When found in such places, it is impossible..." impossible to take them, from their wonderful agility, and their evading all pursuit by bounding into the thick- cover they can find."

That the Canadian, as well as the Siberian Jerboa, sleeps through the winter, seems evident from a specimen having been found, towards the end of May, inclosed in a ball of clay, about the size of a cricket ball, nearly an inch in thickness, perfectly smooth within, and about twenty inches under ground. It was given to the General; who proceeds thus:

"How long it had been under ground it is impossible to say; but as I never could observe these animals in any parts of the country after the beginning of September, I conceive they lay themselves up some time in that month, or beginning of October, when the frosts become sharp: nor did I ever see them again before the last week in May, or beginning of June. From their being enveloped in balls of clay, without any appearance of food, I conceive they sleep during the winter, and remain for that term without sustenance. As soon as I conveyed this specimen to my house, I deposited it, as it was, in a small chip-box, in some cotton, waiting with great anxiety for its waking; but that not taking place at the season they generally appear, I kept it until I found it begin to smell: I then fluffed it, and preserved it in its torpid position. I am led to believe, its not recovering from that state arose from the heat of my room during the time it was in the box, a fire having been constantly burning in the stove, and which, in all probability was too great for respiration. I am led to this conception from my experience of the snow bird of that country, which always expires in a few days (after being caught, although it feeds perfectly well) if exposed to the heat of a room with a fire or stove; but being nourished with snow, and kept in a cold room or passage, will live to the middle of summer."