4:18 
VEETEBRATA. 
Genus APLODONTIA : Aplodontia. — Of this there is a single species, the Sewellel of Lewis 
and Clark — the Arctomys rufa of Griffith's Cuvier — A. leporina^ digging burrows and living in 
small societies in the neighborhood of the Columbia River, and abundant near the Great Falls. 
It is about the size of the gray rabbit, being foiirteen inches long, with a tail half an inch long. 
It is of a reddish-brown color, and has no cheek-pouches; the eye is small, and the fur thick and 
soft, resembling that of the musquash. The skins are rnuch nsed by the Indians for robes. It 
feeds on vegetables, and is said occasionally to climb trees, but ordy for a short distance, as is the 
case with the woodchuck. It produces four to five young at a birth. 
The preceding genera belong to the Saccojjhoriens ; the following to the Saccomyens. 
Genus SACCOMYS : Saccomys. — Of this there is a single species, the S. anthophilus, found 
in South America. It is of the size of a common rat, and of a brownish-fawn color; feeds chiefly 
on flowers, and has large sacks opening externally at the sides of the mouth. 
Genus IIETEROM YS : Heteromys, including two species. — Thomson's Heteromys, the Mus 
anomalus of some authors, which is of a brownish chestnut-color, has weak spines mingled with 
its hair, and a very long, scaly, black tail. It is of the size of the common rat, and is found in 
the Island of Trinidad, West Indies. Desmarest's Heteromys is four inches long, with a tail 
a trifle shorter. It is of a nut-brown color, has rough hair, and moderate-sized cheek-pouches. 
It is found in Colombia. 
PEDETIENS OF SOUTHERN AFBICA. (SeC p. 421.) 
Genus DIPODOMYS : Dipodo7mjs.—Th.h term is from the Greek dipous, two-footed, and mus, 
a mouse, and alludes to the fact that the animals to which it is applied move on two feet. They 
are in fact a kind of Pouched Jerboa-mouse, having long hind-legs, on which they move like i\w. 
