and allied East- African Species. 351 



greyisl), faintly tinted with pale buff. Under surface of body 

 whitish ; hairs with grey bases and white tips. Tail short, 

 coloured much as in prceceps ; ventral surface less buffy. 



Skull small, in size hardly larger than that of somalicus. 

 Molar teeth much smaller than in the allied species. 



Dimensions in millimetres (measured in the flesh) : — 



Average of 



10 adults. Max. Mia. 



Head and body 132 140 128 



Tail 95 107 88 



Hind foot 25-8 27 23 



Adult skull (type) : greatest length 31'8 mm.; basilar length 

 26*1; condylo-incisive length 30; zygomatic breadthlG; inter- 

 orbital constriction 4 3 ; squamosal breadth of cranium 13"2; 

 length of nasals 12; palatilar length 14'3; length of palatal 

 foramina 7; alveolar length of upper molar series 5*9. 



J'ype locality. Rumruti, Laikipia Plateau, British East 

 Africa. 



Type in British Museum. Original number 1413. Col- 

 lected by Mr. Robin Kemp on October 25th, 1910. 



The type locality is at present the only district in which 

 this species has been found. It does not appear to occur 

 either at Baringo on the west side or in the Eusso Nyiro 

 district to the east of Eumruti, since Mr. Kemp found only 

 A. praceps at Baringo and chanleri and reptans in the Eusso 

 Nyiro district. Probably this small liumruti species is con- 

 iiued to the high altitudes of the Laikipia Plateau. 



(15) Arvicanihis somalicus, Thos. 

 Arvicanthis somalicus, Thomas, P. Z. S. 1902, ii. p. 312. 



In size about equal to rumruti ; general colour sandy buff, 

 mixed with brownish black. 



Size of body and tail about as in the foregoing species ; 

 hind foot rather smaller, average length 24 mm. General 

 colour pale sandy buff, lined with black and pale brown. 

 Flanks paler and yellower than "back. Nose, ocular rings, 

 and ears orange-buff. Backs of hands and feet buffy white. 

 Ventral surface of body white, hairs with grey bases and 

 white tips. Flanks fairly distinctly marked oft' from belly, 

 though this character is not evident in the type, which 

 appears to be rather a bleached specimen. Tail short and 

 similar in colour to that of the Rumruti species. 



Skull small, rather less than in rumruti. Brain-case and 

 audilory bulljB much smaller than in the abyssinicus group. 



