168 Mr. G. Dollman 07i the 



very different animal, and not in any way closely related to 

 jacicsoni, a species that is probably only found at the very top 

 of the mountain. 



(20) Otomys percivali, sp. n. 



Agrees with jacksom in that m^ possesses 7 laminae, but is 

 very much larger in size, paler in colour, and the general form 

 of the skull considerably more arched than in the Elgou 

 species. Size much larger ; head and body 160 mm, in 

 length. Colour of dorsal surface bright ochreous buff suffused 

 witli brownish, the general effect yellower and brighter than 

 in dartmouthi. Flanks rather lighter and yellower than back. 

 Face and head bright yellowish buff. Eyes surrounded with 

 orange-coloured rings. Long hairs in front of ears with dark 

 bases and orange-buff tips ; hairs directly behind ears with 

 creamy-white tips, somewhat as in the thomasi group. Backs 

 of hands and feet dirty white. Ventral surface of body much 

 as in dartmouthi. Tail brownish orange above ; dull orange- 

 buff below. 



Skull with interorbital region markedly arched, muzzle and 

 cranial lines considerably depressed. Auditory bullse and 

 teeth very much larger than in Jacksoni; m^ with 7 lamina? 

 and, as in all the other members of this division, the lower 

 incisors marked with two deep grooves, the inner one rather 

 less deeply cut than the outer, but very much more so 

 than in any of the forms in Division B, ^'. e. the tropicalis, 

 thomasi, and orestes groups. 



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



Head and body 160 mm. ; tail 88; hind foot 27 ; ear 23. 



Skull : greatest length 39'7 ; basilar length 32-2 ; con- 

 dylo-incisive length 37 ; zygomatic breadth 20*6 ; interorbital 

 constriction 3*5 ; squamosal breadth of brain-case 14 ; length 

 of nasals 17 ; greatest width across expanded part of nasals 

 6*5; breadth across middle of nasals (taken just behind the 

 expanded anterior portion) 4 ; depth from highest point of 

 orbit to alveolar border at front of m^ 13*7; palatilar length 

 18'1; length of palatal foramina 7 ; post-palatal length 14*5 ; 

 length of upper molar series from anterior alveolar border to 

 back of last molar 10*5 ; length from anterior base of enamel 

 on vi^ to back of m^ 9'5 ; greatest width of /?i^ 2*7. 



Hah. Twelve miles south of Lake OlboUossat, Naivasha 

 District, B.E.A. Altitude 8700 feet. 



Type. Old female. B.M. no. 12. 7. 1. 424. Original 

 number 509. Collected by A. Blayney Percival, Esq., on 



