612 



MR 



W. L. SCLATER ON A NEW JERBOA. [NoV. 4, 



Behind the large anterior palatine foramina there are found, 

 between the posterior molars, a large pair of posterior palatine 

 foramina, which are only represented by very minute passages in the 

 other Jerboas. 



The very large size of the bullae in Euchoreutes causes them 

 nearly to meet in the median line, where, as in all other Jerboas, 

 there is a considerable interval between the two bullae in the region 

 of the basioccipital. 



In the lower jaw of Alactaga there is between the condyle and 

 the angle an outwardly and backwardly projecting thick process of 

 bene, which is very conspicuous in all the species of that genus that 

 I have been able to examine ; this process is quite unrepresented in 

 Euchoreutes. 



The dentition of Euchoreutes is similar to that of Alactaga, and 

 consists of one premolar and three molars above, and three molars 

 below ; the crowns of the molars, however, are much shorter, and 

 the cusps much longer and sharper than those of other Jerboas. 

 The incisors, as in Alactaga, are not grooved. 



The following measurements are in inches and decimals : — 



Total length from snout to base of tail 3"2.5 



Tail to end of vertebrae 5'8.5 



„ with hairs 6*40 



Length of ears from vertex 1'55 



Distance from snout to ear (in extracted skull) . . 1'20 



Fore limb from elbow-joint to end of toes 1*10 



Tarsus to end of 1st digit 1"15 



„ „ 2nd „ 1-65 



3rd „ 1-70 



„ „ 4th „ 1-65 



5th „ MO 



Total length of skull M5 



Breadth of zygoma '50 



,, at brain-case '53 



„ at interorbital constriction '30 



Length of nasals "45 



Anterior palatine foramen '20 



Length of molars and premolars "20 



„ lower jaw from the condyle to the incisors '70 



Habitat. The two specimens of Euchoreutes naso were procured 

 by the Hon. Charles Ellis, during his journey through Eastern or 

 Chinese Turkestan, and presented to the Indian Museum. They 

 were probably obtained by him in the sandy plains round the city 

 of Yarkand, but no exact locality is attached to them. 



The new genus Euchoreutes belongs essentially to the Dipodinee 

 as defined by Alston (P. Z. S. 1876, p. 89), of which subfamily it 

 will form a fourth genus. I subjoin a table of the principal charac- 

 ters of the four genera. 



