52 Dr. N. Severtzoff on the Mammals of Turhestan. 



mottled appearance is not so easily noticed ; but the width 

 and number of these rings on the liair of S. brevicauda is 

 also variable. 



Therefore it would be useful to make more exact comparisons 

 between S. mugosaricus, S. brevicauda, and S. musicus, the 

 ranges of which meet on the Lower Volga and Don ; and 

 perhaps they may prove to form only one species. Here it 

 also must be stated that the first description of -S'. mugosaricus 

 was taken by Lichtcnstein from a specimen from the Kirgies 

 steppes ; whilst the first description of S. musicus was made by 

 Iklenetri^s from a mountain specimen from the Caucasus. The 

 Karabur specimens were obtained at an altitude of from 7000 

 to 9500 feet, on the grass-covered plains of the summits of the 

 Karabur ^lountains. 



40. Arvtcola arvalis. 



Inhabits the north-eastern portion of Turkestan, and does 

 not appear to go beyond an altitude of about 6000 feet. 



41. Arvicola leucura, sp. n.* 



Is found in the north-western parts of Tui-kestan. It goes 

 exactly as high as the preceding species, but has not been 

 observed below 1000 feet altitude. 



The fur is soft like that of Cricetus, light brownish grey, on 

 the belly white ; the base of the hair on the whole body is 

 plumbeous. The ears project beyond the fur. The tail is one 

 fourth as long as the body, and is snowy white, with a black 

 tip of rather longer hair. The first lower molar tooth has 

 nine prisms, like i\\a.t oi Arvicola. 



The most striking specific characters are in the white tail 

 and soft hair ; and the species may thus be diagnosed : — 



Arvicola Cauda nivea subpenicillata, apice obscuriore, vellere moUi 

 cinerascente, infra albo, auriculis e vellere prominentis. 



I obtained only one specimen, on the Upper Massat in the 

 lower mountains of the Thian, between Aulje-ata and Chim- 

 kent, in December 1866. 



42. Arvicola gregalis. 



Has been observed in the same localities as the preceding 

 species. I myself met with it in the Karatau at the upper 



* [Should this prove to be a good species it will require a new name, 

 A. leuc^irus having been used by Gerbe (Rev. Zool. 1852, p. 260) for a 

 European vole which Blasius and Fatio consider to be identical vrilh 

 A. mvalisoi Martins. — E. R. A.] 



