66 EATS AND MICE. 



Before discussing the jerboas, a small jumping mouse must be men- 

 tioned. It is called Zupus firtcJinanua vicinti^, and occurs in South- 

 western Kansu, but so far none have been recorded elsewere in North 

 China. There are three other species found in Szeehuan. 



The Ordos Jerboa (Di-pus sotverbyi). 



The most striking jerboa is the Ordos jerboa (Dipus sowerbyi), 

 which was discovered by me in 1908 in the Ordos Desert. This animal 

 is about five inches long in the body, and has very long hind legs, 

 very short front legs and a long tail with a fine tuft ati the tip like 

 an arrow feather. In colour it is of a sandy yellow with white belly 

 and rump. Its chief characteristic is that it has only three toes on 

 the hind foot. It lives in burrows in the sand, progresses by means 

 of enormous jumps, sometimes eight feet in length, and feeds upon the 

 seeds and tender shoots of the sage brush. It is easily tamed and 

 makes a splendid pet, playing and skipping about the room without 

 the least sign of fear. Tlie Chinese name is Tiao-er (Jumper). 



The other species is tlie alactaga (Ahctnga vumgolica), which 

 inhabits Inner Mongolia and parts of North Chihli and Shansi. The 

 animal is somewhat larger than the Ordos jerboa, has very much longer 

 ears, is of a greyer colour, and has five instead of three toes on the 

 hind feet. Otherwise the two species are very much alike, and have 

 similar habits, except that the alactaga lives in grassy country. 



The third form (Alactnga viotigoJica longior) was discovered by me 

 in Kansu, and it is a subspecies of that from ]\Iongolia. It differs only 



