2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 68 



Remarks. — In a large collection of specimens of multimammate 

 rats from many parts of eastern Africa, the series of nineteen skins 

 from Kaimosi is conspicuous on account of the generally dark color 

 above and because of the absence of any specimens with light-colored 

 underparts. The skins and skulls average larger in size than those of 

 neighboring forms. The new subspecies is most closely related to 

 Rattus concha iingandce (de Winton), described from Entebbe and 

 represented in the National Museum collection by numerous 

 examples from the north shore of Victoria Nyanza and Unyoro. 



PEDETES SURDASTER LARVALIS, subsp. nov. 



Type from Ulukenia Hills, Athi Plains, British East Africa ; adult 

 female, skin and skull, U. S. Nat. Museum No: 163304. Collected 

 November 21, 1909, by J. Alden Loring. Orig. No. 8250. 



Diagnosis. — Like Pedetes surdaster surdaster of the Naivasha 

 Plains but less richly colored and skull with much deeper face. A 

 supraorbital elevation on each side of the median depression in 

 frontals, on the anterior portion of frontal bone and at the base of 

 nasal, gives the profile view an evenly rounded outline from mastoid 

 to nasal [in typical surdaster the braincase is higher and the sinciput 

 low, so that a profile view presents a very uneven line, much raised 

 posteriorly and with a decided depression over the lachrymal region 

 in the center]. ]\Iost of the bones of the face are involved in the 

 producing of the much greater depth of the entire anterior portion 

 of the skull, which is conspicuous when compared in profile or from 

 anterior view with skulls of typical surdaster. The rostrum is much 

 deeper and the antorbital region, including the foramen and ant- 

 orbital plate, much higher and comparatively narrow. Suture 

 between frontals and parietals nearly straight across skull, with only 

 slight anterior convexity [in surdaster always with distinct and 

 usually pointed salient]. Size essentially as in surdaster. 



Measurements of type. — Head and body, 370 mm. ; tail vertebrae, 

 427; hind foot, 159; ear, 82. Skull: Condylobasal length, 78.2; 

 zygomatic breadth, 55.2; greatest breadth nasals, 21.7; height of 

 skull in front of orbits, from anterior alveolar border to highest 

 point on crown directly above lachrymal bone, 36.2 [in numerous 

 specimens of typical surdaster, 30.5 to 32.4] ; mastoid breadth, 45.4; 

 up])er tooth row, crowns, 16.3. 



Remarks. — Four specimens of this new form from the Athi Plains 

 have been compared with forty-six specimens of Pedetes surdaster 

 surdaster from Naivasha Station, near the type locality. 



