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Show 148 MAMMALIA. nd roots. The limbs are short; there is scarcely any tail; and :he eyes arc excessively small. From Siberia; where it alw~ys lives under ground like the Mole and Rat-Mole. It feeds prmcipally on the bulbs of different Liliacere. The third species, like the other animals comprised in the great genus of Rats, has merely the rudiment of a thumb on the fore foot. G. ltudsonius; Mus ltudsonius, Gm., Schreb. CXCVI. (The Lemming of Hudson's Bay.) A light pearly-ash colour; without tail or external ears; the two middle toes of the fore foot of the male seem to have double claws, which is owing to the skin at the end of the toe being callous and projecting from under the nail, a disposition of the part hitherto unknown, except in · this animal. It is the size of a Rat, and lives under ground in North America. 0ToMYs, Fred. Cuv. The Otomys are nearly allied to the Field Rats, and have also three grinders, but they are composed of slightly arcuated lamince arranged in file.(l) Their incisors are grooved with a longitudinal furrow, and the tail is hairy, as well as the ears, which are large. 0. capensis, Fred. Cuv. (The Cape Otomys.) Size of a Rat; fur marked with black and fawn coloured rings ; tail a third shorter than the body.(2) DrPus, Gm. The Jerboas( 3) have nearly the same kind of teeth as the true Rats, except that there is sometimes a very small one immediately before the upper molars. The tail is long and tufted at the end; the head large; the eyes large and prominent; but their principal character consists in their posterior extremities, which, in compari· son with the anterior, are of a most immoderate lengtl), and above all, in the metatarsus of the three middle toes, which is formed of one single bone, resembling what is called the tarsus in Birds. It is from this disproportion of the limbs that they were named by the ancients Biped Rats, and in fact they seldom move otherwise than by great leaps on their hind feet. There are five toes to each of the ( 1) They are exact models, in miniature, of the grinders of the Elephant. (2) lt is the same animal described and represented in the essay on the genus of Rats, by M. Brantz, Berlin, 1827, under the name of Euryotis irrorata. (3) There has lately appeared an excellent paper on the Jerboas, by M. Lich· tenstein, in which that learned naturalist describes and figures ten species. I can only rcfct· my readers to_ the paper itself. It is inserted in the Journal of the Acad. of Berlin. RODENTIA. 149 fore feet, and in certain species, besides the three great toes to the hind feet, there are small lateral ones. They live in burrows, and become torpid during the winter. D. sagitta; M. sagitta, L.; Buff. Supp. VI, xxxix and xi. The Jerboa has only three toes, and is the size of a Rat; a light fawn colour above; white beneath ; tuft of the tail black, the tip white. Is found from Barbary to the north of the Caspian sea. D. hertipes, Licht. (The Hairy-footed Jerboa.) The head more compt·essed ; only three toes to the hind feet, as in the Jerboa, but they are 'more hairy. From Africa.(!) D.jaculus; M. jaculus, Pall. Glir. XX, Schreb. CCXXVIII. (The Alactaga.) Two small lateral toes ; ears longer than those of the Jerboa, but is nearly of the same colour. Pallas has observed them of three sizes, from that of a Rabbit to that of a Rat: they are probably as many species.(2) One or the other is found from Barbary to the Eastern Ocean, and as far as the north of India. HELAMvs, F. Cuv.-PEDETEs, Illig.(3) The Jumping Hares, like the Jerboas, have a large head, and great eyes, a long tail, and the anterior part of the body extremely small, in comparison to the posterior, although the disproportion is much less than in the true Gerboas. The peculiar characters of the Helamys are four grinders every where, each one composed of two lamince; five toes to the fore-feet, armed with long and pointed nails, and four to their great hind ones, all separate, even to the bones of the metatarsus, and terminated by large nails, almost resembling hoofs. This number of toes is the inverse of that most common among the Rats. Their inferior incisors arc truncated, and not pointed like those of the true Jerboas, and of the greater part of the animals comprised under the genus of Rats. One species only known, the H. caffer.; Mus. caffer., Pall.; Dipus ca./fer., Gm., Buff. Supp. VI, xli, and better, Fred. Cuv. Mammif. It is the size of a Hare, of a light fawn colour, and has a long tufted tail, with a black tip. Inhabits deep burrows at the Cape of Good Hope.( 4) ~!)Add the Dip. telum, D. platurus, and D. lagopus of Eversman, Voy. de , yendorf en lloucarie, p. 390. ( 2 ) Pallas has latterly distinguished the small Alactagas by the name of JJip. ((3) Pedetes, jumper, llelamys, Jumping-Rat. 4 ) &e./lppend. XI of .11m. Ed. |