80 CLASS MAMMALIA. 



The Helamys, F. Cuv. (Pedetes, Illig.) 



Which have been hitherto classed with the Ger- 

 boas, resemble them in fact, in the large head, large 

 eyes, long tail, and more especially by the smallness 

 of the fore extremities and the iength of the hinder, 

 although the disproportion is much less than in the 

 true Gerboas. The peculiar character of the Hela- 

 mys, are four cheek-teeth throughout, composed each 

 of two laminae ; five toes on the fore feet, armed 

 with very long and pointed nails, and four upon 

 their large hinder feet, all distinct, even in the bones 

 of the metatarsus, and terminated by large nails, 

 almost resembling hoofs. The number of toes is the 

 inverse of that most general among the rats. Their 

 lower incisors are truncated, and not pointed^ like 

 those of the true Gerboas, and all other animals 

 comprised under the Rat genus, the Rat-Moles alone 

 excepted. 



There is but one species known, belonging to the 

 Cape of Good Hope, as large as a Rabbit, of a clear 

 fawn-colour, tufted tail, black at the end, ( Mus Cqfer, 

 Pall., Dipus Cafer, Gm.) Buff. Supp. VI. xli. 



Gmelin has already separated from the genus of 

 Rats, 



The Marmottes, (Arctomys, Gm.) 



Which with the pointed lower incisors of the other 

 animals comprehended in this great genus, have five 

 cheek-teeth on each side above, and four below; 

 bristling with points ; accordingly some species are 



