Mammals of the 1021 Mount Eoerest E.rpediti'on, 181 



20*5; nasals 10"7x.'^; inferoi-bital hreadth 4*4; l)rea<lbli of 

 biain-CHSo 11/7; palatal torainina 5"2 X 1*0 ; dental loiigtii 

 12*() ; clieck-teetli (crowns) 4*1. 



llab. Tibet. Only known from Tini^ri, 14,000'. 



Ti/pe. Adult male. Original number 30. Collected by 

 Mr. A. F. 11. Wollaston, July 7, 1921. 



Tliomas described G. aJticola from Sliushal on the Pang- 

 Kong Lake, Ladak, where it is fouhd at an altitude of 

 13,500'; and it also occurs in the valley of the Upper Sutlej 

 at Teza. 



5. Pha'iomys leucurus^ Blyth. 



1863. Phaiomys leucurus, Blyth, J, A. S. B. xxxii. p. 89. 

 1879. Arvicola bU/thi, Blanford, Sci. Res. Second Yarkand Miss., 

 Mammals, p. 39 [^Microtua (^Phaiomys) blylhi of subsequent writers]. 



S. 1. Tinki Dzong, Tibet, 13,500', 17th June. 



S. 3, 10, 12, 20, 23, 27, 2S, 29, & 31 in adult pelage, and 

 4, 5, 6, 7, 8, & 9 juv. ; ? . 2, 11 both adult. Tingri,' Tibet, 

 14,000', 25th June (o lOtli July. 



Blyth based his genus Phaiomys upon the present species. 

 Blanford regarded Phaiomys as a synonym of " Arvicola " 

 ( = Microtiis in current nomenclature), while subsequent 

 writers have given it no more than subgeneric rank. In the 

 genus Arvic(jla the s[)ecific name " leucurus" is preoccupied 

 by A. leucurus, Gerbe, 1852 ; and therefore Blanford substi- 

 tuted the name " hlythi" for that originally bestowed upon 

 the present species by Blyth. But, in our opinion, Phaiomys 

 is entitled to full generic rank ; and, if this be the case, the 

 specific name leucurus, given to the genotype by Blyth, is 

 valid and must be restored. 



Phaiomys, though still imperfectly known, is one of the 

 most interesting microtine genera. By the peculiar combina- 

 tion presented by its external, dental, and cranial characters 

 it is sharply distinguished from all its allies — although, taken 

 .singly, each of its characters can be found in other groups. 

 Tliu:?, as regards externals, the curious lemuiing-like form of 

 these voles and their lengthened fore-claws can be matched 

 among that little group of Central-Asiatic species of which 

 M. brandd is a good example ; the latter, uouever, differs 

 widely in skull and teeth from the present genus. In certain, 

 though not in all, respects, the cranial and dental characters 

 of Phaiomys, as here understood, find their .match in the 

 North-American Pedomys and in the Eurasian Arvicola, 

 genera of wholly dissimilar external appearance. Although 

 detailed discussion of this interesting matter must be reserved 



