40 



SKETCH OF THE HISTORY OF MAMMALIA. 



mounted horseman on a fleet steed can scarcely overtake 

 it. The fur of the Alactaga is extremely soft and fine ; 

 on the upper parts it is of a pale fawn-yellow, clouded 

 with grayish brown on the lower part of the back ; a 

 white crescentic line extends on each side of the crupper, 

 below the root of the tail. The under parts of the body 

 and inside of the limbs are white ; the tail is brown, 

 except the tuft at the extremity, which is black tipped 

 w ith white. 



24. — Teeth of Labrador Jumping Mouse. 



The Labrador Jumping Mouse 



(^Meriones Labradoricus), 



This species appears to be the Labrador Rat of Pennant ; 

 the Gerbillus Hudsoniiis of Rafinesque ; Mus Labradorius 

 of Sabine ; Gerbillus Labradorius of Harlan ; the La- 



