914 ßOBERT COLLETT, 



differences in the formation of their skulls, which I shall subsequently 

 treat of. 



The colour is a pe^uliar mixture of yellowish green and grey; 

 the hairs are ashy grey at the base, but towards the ends they be- 

 come first white, and theu, ou the tips, yellow with a silken gloss. 

 The middle of the back is darker, almost brownish black, but 

 here likewise the hairs have yellowish tips; two irregulär stripes of 

 silky white extend downwards to the root of the tail ; a narrow black 

 line runs from the occiput along the middle of the nape, and con- 

 tinues somewhat indistinct in the dark central stripe between the 

 two whitish ones. Thus, when viewed in a favourable light, the back 

 appears to have tree dark and two whitish longitudinal stripes. 

 The lower parts are white, the chin gi^eyish white. 

 The snout ashy grey ; a white semilunar spot under the ear, and 

 a small pale yellowish one close above and under the eye. 



The limbs are yellowish grey, the base of the hairs grey, like. 

 the back ; the fore limbs whitish on the inner side. Claws pale yellow. 

 The tail on its first two thirds (the woolly part) is yellowish 

 grey above and beneath ; there is, however, a large patch on the upper 

 side without the yellowish glossy tips, so that the grey grounding is 

 only visible there (possibly worn ?). The apical third (the short haired 

 part) is whitish, but without sharply defined limits of colour. 

 The ears are brownish black, externally bordered with white. 

 The skull: 



Length 65 mm 



Width 39 



Length of lower jaw 48 „ 



Length of dental series in upper jaw 33,5 „ 



Length of dental series in lower jaw 25 „ 



Breadth of nasale in front 2,5 ., 



Greatest breadth of nasale behind ....... 6 „ 



In the formation of its skull it approaches Ps. albertisii^ figured 

 by Peters and Doria in: Ann. Mus. Genova, vol. XVI, tab. VIII, 

 and IX; but in this latter species the two crests on the parietalia 

 evenly converge towards the back. Moreover ci in the upper jaw is 

 smaller than * 3 ^ and closely adjoins p i , whilst in Ps. archeri the 

 reverse is the case. 



Finally the upper profile of the skull difiers in both species, be- 

 sides the nasalia being less dilated behind in Ps. archeri, than in the 

 other species. 



