5() Dr. N. Severtzoft' on the Mammals of Turkestan. 



difters from the adult only by its smaller size and the propor- 

 tionally smaller tail-tuft. 



M. opimm, which has been collected in great numbers on 

 the Ilcy, near Ilodgent, and lower down at the Sjr-Darja, 

 has sometimes a sharply marked black line running from the 

 tail-tuft along the upperside of the tail almost to its root ; this 

 line, however, is very variable in its length. 



According to the characters and distribution it appears to 

 me that J/. colUum is the general origin of the steppe gerbilles 

 (3/. tamanciniis and M. opi'mus), wdiich inhabit the bottom of 

 what, geologically speaking, was at no distant period a lake ; 

 as well as of M. Jyhicus^ which, in its dentition, comes closer 

 to M. collium than is M. opim^cs, and perhaps has been driven 

 out by the latter to the south-west. 



But up to the present time the limits of the ranges of M. 

 opimus and M. lyhicus are unknown ; they probably meet 

 in the deserts of Persia or Syria *. 



52. Dipus jaculus. 



Has been found by me almost all over Turkestan, being not 

 rare in the eastern parts and very common in the north- 

 western districts, where it appears to be a resident at an alti- 

 tude of from 1000 to 4000 feet above the sea, i. e. in the cul- 

 tivated distiicts. 



53. Dipus acontion. 



54. Dipus sagitta^ var. telum. 



55. Dipus lagopus. 



56. Dipius platyurus. 



These four species have been observed in the low plains 

 at the mouth of the Syr-Darja, at the sources of the Aris, and 

 about Lake Aral as residents. 



57. Ellohius talpinus^ var. rufescens. 

 Has been met with by me throughout the east and north of 



* [In his list Dr. Severtzoff originally named this species Meriones mon- 

 tanus; but having discovered that this name was preoccupied by Sir 

 Andrew Smith for a South-African species, he renamed it (at p. 83) 

 Meriones colliwn. — F. C. C] 



[Mr. Blanford describes an interesting new species from Eastern 

 Turkestan, which he names Gerbillus cryptorhinus, from the remarkable 

 semicircular flap which covers the nostrils (Journ. Asiat. See. Beng. xliv. 

 p. 108).— E. E.A.] 



