SQUIRRELS, MARMOTS AND PIKAS. 81 



Further west in North Shansi, in the Ordos Desert and in North 

 Shensi this species is replaced by another lighter form known as 

 0. bcdfordi. This was described from specimens taken by Anderson 

 and myself in West Shansi. Its chief characteristics are its very much 

 paler pelt and slightly larger size, while the skull was described as 

 being slightly larger, less convex on the forehead, with larger brain-case, 

 very much larger bullae, and as being broader than in 0. dauurica. These 

 pikas we found occupying sites at various altitudes in the loess hills. 

 Some were in colonies on the plains and in river valleys, while others 

 would be located in the deep loess gullies and ravines or on the steep 

 sides of the hills. Specimens from Yen-an Fu in North-central Shensi 

 agree in skull measurements with those from the type locality (Ning-wu 

 Fu) in West Shansi, but the winter pelts are somewhat different. 

 Those from Shansi are somewhat darker and more ochraceous In 

 colour than those from Shensi. 



On the Clark expedition in 1909 I secured specimens in Eastern 

 Kansu of yet a third species, which was called 0. annectens by Dr. 

 Gerrit S. MiUer of the U.S. National Museum. This species, though 

 resembling the Shensi pika, is somewhat smaller, and has smaller 

 bullae and more convex upper cranial outline. It was only in. Kansu 

 that I ever saw pikas playing about in broad daylight, and I was 

 ;8truck by their remarkable resemblance to rabbits in the way they 

 paoved and fed. I secured some live ones, which I tried to tame, but 

 the little creatures were altogether too timid to endure handling, and 

 refused to eat. 



From Western Kansu Prof. IMatschie has described a species under 

 the name of 0. liuangcnsis, which more closely resembles 0. dauurica. 



In the forests of West Shansi, when on the Duke of Bedford's 

 Exploration of Eastern Asia I discovered a small wood-pika, which 

 was described as new by Mr. Thomas, who gave it the name 0. sorella. 

 Only one specimen was secured at that time, but I secured a second ou 

 a later trip. No other specimens have yet been obtained. This pika 

 is very much smaller than any of those already mentioned. It is 

 considerably darker in colour than 0. dauurica and the hair on the 

 soles of the feet is very dark. It keeps entirely to wooded mountains, 

 amongst the moss-covered boulders of which it excavates extensive 

 and complicated burrows. It seems to be a very rare species. 



Related to it is 0. cansa from Kansu, described by Lyon. This 

 species is larger, however, and has larger bullae and a less convex 

 skill, 

 8 11 



