1900.] MAMMALS FROM MOUNT KENYA. 175 



9. Otomys irroratus Bts. 



a. Western slope of Mt. Kenya, 8000 ft., 16 Sept. 1899. Forest 

 zone. 



b-g. Western slope of Mt. Kenya, 10,000 ft. Bamboo zone. 



These specimens, though as usual differing among themselves 

 in colour, are very uniform in skull-characters and size. Their 

 dimensions, as taken in the flesh, run as follows : — Head and body 

 176-195 mm. ; tail 75-91 ; hind-foot 28-5-31. Like Mr. Jackson's 

 and other East African examples of the species, they all have 

 seven lamina? to the last upper molar. 



10. Otomys irroratus orestes, subsp. n. 



a. (j. Teleki Valley, Mt. Kenya, 13,000 ft., Sept. 3, 1899. 

 Type. 



[6. $ in spirit. Hohnel Valley, Upper Alpine zone, Mt. Kenya, 

 1893 (Dr. J. W. Gregory). 



c, d. Imperfect skeleton and separate skull. Do. do.] 



Size rather smaller, feet slightly and tail decidedly shorter than 

 in the plains form. Colour, of the single skin, corresponding to 

 the greyish and least rufous of the ordinary specimens, rather 

 more mottled than they usually are. 



Skull, as compared with the series from 8000-10,000 feet, 

 smaller throughout, with a shorter muzzle and much shorter, 

 though equally broad brain-case. When viewed laterally, it appears 

 more bowed above and higher mesially. Anterior expansion 

 of nasals not exaggerated. Interparietal smaller, not bowed 

 forwards mesially, its antero-posterior diameter less than the length 

 of the coronal suture instead of greater. Molars rather narrower. 

 Laminae of m. 3 only six in number. 



Dimensions of the type, measured by collector in the flesh : — 

 Head and body 175 mm. ; tail 62 ; hind foot 27 ; ear 20-5. 



Skull : greatest length 39 ; basilar length 31-3 ; greatest breadth 

 20; nasals 17-4 x 7; interorbital breadth 4-6; interparietal 

 4-7 x 9 : palate length from hensilion 167 ; diastema 8-8 ; palatine 

 foramina 7 - 4 ; upper molar series (crowns only) 7-3. 



This is evidently a mountain race of the common East African 

 Otomys, and it was quite to be expected that in the colder climate 

 of what Dr. Gregory calls the " Upper Alpine zone " of Kenya 

 the feet and tail should be shortened, in accordance with the usual 

 rule in such cases. It is, however, curious that, as exemplified by 

 four examples, the Alpine form should have a lamina less in the 

 last molar. Otomys jacksoni Thos., the Mount Elgon representative 

 of the genus, agrees with the lowland form in this respect. 



The spirit-specimen obtained by Dr. Gregory in Hohnel Valley 

 measures :— Head and body 141 mm. ; tail 63 ; hind foot 24 (26-5 

 cum ungue) ; ear 21. Its mamma? number — 2 = 4. 



Type. B.M. No. 0.2.1.21. 



Although Dr. Gregory was the first discoverer of this form, his 

 specimens could not be distinguished before owing to the fact that 



