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 xl. 
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 Cas- 
pian sea. 
D. hertipes, Licht. (The Hairy-footed Jerboa.) The head 
more compressed ; only three toes to the hind feet, as in the 
Jerboa, but they are more hairy. From Africa.(1) 
D.jaculus ; M. jaculus, Pall. Glir. XX, Schreb. CCX XVIII. 
(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. 
Hexamys, F. Cuv.—Peperss, 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 
laminz ; 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 are 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 
‘is known, the 
HI, caffer.; Mus. caffer., Pall.; Dipus caffer., Gm., Buff. Supp. 
VI, xli, and better, Fred. Cuv. Mammif. It is the size of a 
F 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) — 
(1) Add the Dip. telum, D. platurus, and D. lagopus of Eversman, Voy. de 
-Mayendorf en Boucarie, p. 390. 
(2) Pallas has latterly distinguished the small Alactagas by the name of Dip. 
acontion. 
(3) Pedetes, jumper, Helamys, Jumping-Rat. 
» (4 See Append. XI of dm. Ed. 
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