NO. 7 MAMMALS FROM EQUATORIAL AFRICA — HELLER II 



OENOMYS HYPOXANTHUS VALLICOLA, new subspecies 



Naivasha Rusty-nosed Rat 



Type from Lake Naivasha, British East Africa; adult female, 

 mimber 162614, U. S. Nat. Mus. ; collected by J. Alden Loring, July 

 15, 1909; original number 6640. 



Characters. — This is a much lighter and smaller race than bac- 

 chante of the Man and Kikuyu escarpments bounding the Rift Valley 

 to the west and the east of Naivasha. In coloration it approaches 

 nearer editits of Ruwenzori but is less rufous or rusty and is some- 

 what smaller in body size. The skull is shorter decidedly than that 

 of editus but equals it in zygomatic width. 



Flesh measurements of the type : head and body, 160 mm. ; tail, 

 184; hindfoot, 31. Skull: condylo-incisive length. 34: zygomatic. 

 breadth, 17; interorbital width, 5.5 ; nasals, 4-6 X 15 ; length of upper 

 tooth row, 7; diastema, 10; length of incisive foramina, 7.8. 



Three other specimens from Naivasha are in the collection and 

 they agree in coloration with the type. 



ARVICANTHIS ABYSSINICUS VIRESCENS, new subspecies 

 Olivaceous Grass Rat 



Type from Voi, British East Africa ; adult male, number 183922, 

 U. S. Nat. Mus.; collected by Edmund Heller, November 15, 191 1 ; 

 original number 4775. 



Characters. — Arvicanthis abyssinicus virescens resembles nairobae 

 most closely from which it may be readily distinguished by its darker 

 dorsal coloration, which is heavily lined by blackish hairs having a 

 distinct greenish iridescence. The body size is considerably smaller 

 and the skull shows relatively smaller bullae, and teeth, and narrower 

 and more slender nasal bones. In the tone of its dark dorsal colora- 

 tion it resembles nubilans of the Kavirondo region but it differs 

 from this race by its white underparts and its much smaller body size. 



The flesh measurements were : head and body, 125 mm. ; tail, 103 ; 

 hindfoot, 26 ; ear, 16.5. Skull : condylo-incisive length, 30 ; zygomatic 

 breadth, 16.8; interorbital breadth, 4.8; nasals, 4.8x12; length of 

 upper tooth row, 6.2 ; width of first upper molar, 2 ; diastema, 8.8 ; 

 length of incisive foramina, 6.2. 



The type is unique. It has been compared with a large series of 

 topotypes of both nairobae and nubilans in the National Museum 

 and is readily distinguishable from both of these races. 



