4 SMITHSONIAN M ISCELLANfCOUS COLLECTIONS VOL. 56' 



22; zygomatic breadth, 14; nasal length, 10.8; interorbital constric- 

 tion, 4; diastema, 7.5; maxillary toothrow, 4.8. 



Closely allied to dennice, Thomas, of Ruwenzori, from which it 

 may be distinguished by its much darker coloration, smaller ears, 

 and larger molars. 



This species is found only in the forest region, where it is every- 

 where associated with B. peromyscus. 



TACHYORYCTES REX, new species 



Type from the western slope of Mt. Kenia, altitude 10,000 ft. : 

 adult male; number 163088, U. S. Nat. Mus. ; collected by J. A. Lor- 

 ing, October 7, 1909; original number 7840. 



Coloration. — Dorsal coloration brownish fulvous, overlaid faintlv 

 with blackish posteriorly, tip of muzzle blackish ; hair everywhere 

 (lark slate at base. Under parts lighter, more tawny fulvous, with 

 the plumbeous showing through conspicuously ; small area about 

 mouth white ; throat blackish. Feet broccoli brown, the toes whitish. 

 Tail dusky above, whitish below. 



Measurements. — Head and body, 232 mm.; tail, 59; hind foot, 31. 

 Skull: condylo-basal length, 54.5; basal length, 51; zygomatic 

 breadth, 3(; : nasals, 23x7.2; length of bullae. 11.8; diastetna, 20; 

 maxillary toothrow, 10.5 ; diameter of m\ 4. 



Size large, exceeding all other East African races. This species 

 is most closely allied to auda.r, of the Aberdare Range, in skull 

 characters. Teeth actually larger, but proportionately sotnewhat 

 less, than those of auda.r. Nasals much longer and with lateral re- 

 entrant angles present. In coloration this form is somewhat lighter 

 than audax, and agrees with it further in seldom being stibject to 

 melanism. Compared to annectens, of Naivasha, which nearly 

 equals it in size, the teeth and nasal bones are markedly larger, the 

 basiocciiiital is much broader between the bullae and the mandible, 

 has a much larger condyle and coronoid process, with the incisor 

 capsule placed very much farther forward. It is evident that in the 

 alpine races of this genus the teeth are much enlarged. 



This is an extremely abundant species on Mt. Kenia, where it in- 

 habits a narrow zone at the upper edge of the bamboo forest where 

 the moorland country first makes its appearance. The species is not 

 found immediately below this area in the bamboo or yew forests, 

 but another species appears on the grassy plains at the base of the 

 mountain. 



