444 bulletin: museum of comparative zoology. 



gray shoulder patches. The type and only specimen was trapped 

 among small trees bordering the streamlet known as the Meru River, 

 which here flows through the arid country from Mt. Kenia, to join 

 the Guaso Nyiro. 



Heterocephalus stygius, sp. nov. 



Type.— Alcoholic female, adult, with dry skull, M. C. Z., 12470, 

 from Neumann's Boma, on the northern Guaso Nyiro River, British 

 East Africa; collected 6 August, 1909, by Glover M. Allen. 



General Characters. — Externally much like H. glaber but with a 

 slightly longer tail; nasals more than one third the occipi to-nasal 

 length, zygomata evenly bowed out anteriorly, as in dunni; coronoid 

 process short, its summit just reaching a line drawn from the tip of 

 the condyle to the point of the incisor. Third upper molariform 

 tooth markedly the smallest. 



Description. — General external appearance as in H. glaber. Skin 

 dark pigmented but naked except for scattered bristle-like hairs, 

 which are most numerous about the mouth. These are short on the 

 front of the muzzle and increase in length on its sides. The longest 

 are a group of three hairs on the side of the face below and just behind 

 the eye. There are a few short hairs on the back, belly, legs, and tail, 

 and a fringe of stiff short bristles on the margins of the toes except on 

 the outer side of the fifth digit of the pes. All these hairs are un- 

 pigmented. On the inner side of each thigh is a small glandular 

 patch. The ear conch is vestigial but projects about a millimeter 

 from the side of the head. 



Skull. — The skull is similar to that of H. glaber as figured (X 2) by 

 Thomas (Proc. Zool. soc. London, 1885, pi. 54, fig. 5) except that the 

 nasals are longer in proportion exceeding one third of the occipito- 

 nasal length of the skull, and the zygomata are more evenly bowed 

 out in their anterior portion, thus approaching H. dunni. The 

 sagittal crest is well marked and extends forward from the occipital 

 ridge for about one half the length of the braincase whence the supra- 

 orbital ridges diverge to the anterior corner of each orbit. 



The teeth appear to differ slightly in their conformation from those 

 of H. glaber, if the description and figures of Parona and Cattaneo 

 (Ann. Mus. civ. Genova, 33, pi. 13, figs. 7, 8) are accurate. All the 

 upper molariform teeth are figured as of essentially the same size in 

 H. glaber though described as diminishing slightly from the anterior 

 to the posterior end of the series, and as having a single external 



