May and August. At pairing time the males fight violently. [Illustration: MOLAR TEETH OF THE MARMOT.] From the Ground Squirrels we pass, by a perfectly natural transition, to the MARMOTS (_Arctomyinæ_), the second sub-family of Sciuridæ. These animals differ from the preceding forms by their broader incisors, shorter tail, and stouter form of body, and by having the third finger longer than the rest. The first upper molar, also, is larger and more persistent than in the Squirrels, and the other molars differ in structure (_see_ figure). The Marmots are all terrestrial animals, living and storing provisions in burrows, which they dig in the ground, and they are strictly confined to the northern parts of the two hemispheres. [Illustration: STRIPED SPERMOPHILE, OR GOPHER.] [Illustration: BURROWS OF THE PRAIRIE DOG.] The nearest approach to the Squirrels is made by the SPERMOPHILES (_Spermophilus_), several species of which occur in North America from Mexico to the Arctic regions, but never to the east of the great central prairie region; whilst in the Old World their domain extends from Silesia, through Russia, and across Asia, to the Amoor and Kamstchatka. The Spermophiles are Squirrel-like in form and have rather short tails, but in the American species this organ is generally longer than in those of the Eastern continent. On the thumb the claw is either very small or altogether wanting; the two series of molars are nearly parallel, and the mouth is furnished with large cheek-pouches. The ears are very small. These animals live in society, and prefer a dry, sandy, or loamy soil, in which they can easily make their burrows, which terminate in a chamber lined with grass and herbage, and have, besides, side-chambers, in which provisions can be stored for winter use. Like the other species of the family, the Spermophiles pass the winter in a state of partial torpidity. In the summer they are exceedingly lively and playful. Their food consists of roots, berries, and seeds of various kinds, and their winter stores of these articles are carried into the burrows in their large cheek-pouches. The females are very prolific, producing from four to eight young at a birth, and in some cases even as many as ten have been found. The commonest and most widely distributed of the North American species is the STRIPED SPERMOPHILE, or GOPHER (_Spermophilus tredecimlineatus_), a pretty little creature of from six to eight inches long, usually of a chestnut brown colour with seven yellowish-white lines running along the back and between these six rows of small squarish spots of the same colour. This species extends its range from the Red River in Canada southwards as far as Texas, and is common on the prairies east of the Mississippi. This and some other species of the genus are said to be very carnivorous in their habits, preying upon small birds and mammals; and the Gopher was even described as feeding upon the flesh of Bisons,