new Rodents from Kan-su. 721 



median sagittal crest, small teeth, and two re-entrant angles 

 on m^. 



(Size rather less tlian in M. fontanieri. Colour dark 

 drabby, the belly little ligliter ; crown blackened in the 

 type. Hands and feet whitisli, well-haired, but the hairy 

 part terminating at the bases of the digits, the skin covering 

 the bases of the claws naked. Tail proportionally rather 

 short, dull greyish white. 



Skull with the essential characters of the fontanieri-cansus 

 group, in which the occipital region forms a ridged and 

 jnojecting hump behind the transverse masseteric crests. 

 Nasals about equalling the premaxillge posteriorly. Inter- 

 orbital region narrow, its edges, even anteriorly, rounded, 

 not ridged as in all the other species of the group. Masse- 

 teric fossae of the two sides with their inner ridges closely 

 approximated, separated by a groove scarcely half a milli- 

 metre in breadth, and therefore practically forming a median 

 sagittal crest. Transverse crest not immensely developed, 

 and, as usual in this group, obsolete in the centre. Lateral 

 crests on occipital hump well developed, but no median 

 occipital crest present. 



Molars small in proportion to the size of the skull, their 

 structure as in M. cansus, except that there is a well-marked 

 second re-entrant angle on the inner side of m^. 



Dimensions of the type (measured in the flesh) : — 



Head and body 202 mm. ; tail 41 ; hind foot 'f^2. 



tSkull : greatest (condylo-nasal) length 50"3 ; condylo- 

 incisive length 46*2 ; zygomatic breadth o4*6 ; nasals 18'6 ; 

 interorbilal breadth 7'3 ; breadth on transverse crest 30*4 ; 

 palatilar length 22*8; palatal foramina 8"3; upper molar 

 series (crowns) 10"2, (alveoli) 10"6. 



Hah. (of type). 30 miles S.E. of Tao-chou, Kan-su. 

 10,000'. A specimen from Gumansa, Kan-su, collected by 

 G. Grzimailo and received from the St. Petersburg Museum in 

 1892, is believed to be of the same species, but tiie diagnostic 

 parts of the skull are broken away. 



Type. Adult male. B.M. no. 11. 11. 1. 1. Original 

 number 172. Collected 6th April, 1911, by Dr. J. A. C. 

 Smith and presented by the Hon. N. Charles Rothschild. 



The close approach of the two masseteric fossae to each 

 other in the middle line is a character quite unique in the 

 genus. The rounded supraorbital margins, small teeth, and 

 the two re-entrant angles on the inner side of m^ also seem to 

 distinguish this species from its allies. 



