DISTRIBUTION OF INSECTIVORES, BATS, AND RODENTS 273 



the Oriental Region and Tachyoryctes in the Ethiopian 

 Region. 



The Pocket-gophers (Geomyidte), which are entirely 

 restricted to the Nearctic Region, contain only two genera 

 and nine species. Allied to them are the Heteromyidx, 

 a more numerous group of seventy or eighty species, 

 entirely restricted to the New World, and, with the excep- 

 tion of a few stray species of Pocket-mice (Heteromys), 

 to the Nearctic Region. 



The tenth family of Rodents, the Bathyergidse, belong- 

 entirely to the Ethiopian Region, over which they are thinly 

 represented by fifteen or sixteen species. The Naked 

 Sand-Rat of Southern Abyssinia and Somaliland (Hctero- 

 cephalus glaber), is one of the most extraordinary-looking 

 Mammals in the world, being almost entirely without hair 

 and covered with a yellowish naked skin ; it is subterranean 

 in its habits. 



The Dipodidte, or Jerboas, which we now come to, are 

 well known for the great length of the hind limbs and the 

 kangaroo-like manner of their progression ; they consist of 

 six genera and about thirty-three species, all of which, 

 except one {Zapus), are restricted to the Palsearctic Region. 

 The six species of Zapus, are spread over the Nearctic 

 Resrion from the far North down to Mexico, where, how- 

 ever, they are restricted to the highlands. 



Allied to the Jerboas is the Jumping-Hare (Pedetes 

 caffer), which forms an allied family of itself, and is re- 

 stricted to Southern and South-eastern Africa. 



We now arrive at the series of Porcupiny Rodents, 

 of which as many as seven families are usually recog- 

 nized. These are mostly found in the Neotropical Region, 



and four of them indeed, the Ghinchillidm, Dasyproctidte, 



s 



