ALLEN: MAMMALS J"IlOM THE BLUE NILE VALLEY. 333 



broader than in T. rohusta. Distally the club-shaped end of the 

 pterygoid is strongly in contact with the large audital bulla. 



Measurements. — The type measured in the flesh: — head and body 

 171 mm., tail 172, hind foot 40.5, ear from meatus 23. Skull: — occi- 

 pitonasal length 44, basal length 37.6, palatal length 24.4, nasals 17, 

 zygomatic breadth 22.5, incisive foramina S, audital bulla 12.3 X 7.2; 

 upper molar series (alveoli) 8, lower molar series (alveoli) 8, upper 

 diastema 12.5. 



Remarks. — This large species seemed rare as we obtained but the 

 single specimen. It was trapped in grass and bushes on the edge of a 

 native grain field. In ^Yroughton's key to this genus (190b), it would 

 come under the second Section, " A. Tail not appreciably longer than 

 head and body." It seems to show no very close relation to either 

 liodon or vallda, the two largest species of this section. Its large size, 

 untufted tail equalling head and body, grooved upper incisors, dark 

 dorsal area, buffy feet, and peculiar shape of the pterygoids are char- 

 acteristic. 



At Fazogli, on the south side of the Blue Nile we obtained a second 

 species of Tatera with untufted tail, which likewise seems undescribed. 

 It may be known as 



Tatera soror, sp. nov. 

 Lesser Blue Nile Gerbille. 



Tijpe.— Skin and skull 14,492 M. C. Z., adult female, from Fazogli, 

 Blue Nile, Sudan. January 16, 1913. 



General Characters. — A smaller species, similar in general colora- 

 tion to T.flampcs above described, but brighter ochraceous, feet white, 

 tail longer than head and body, pterygoids narrowed basally, reaching 

 the level of the hinder edge of the palate. 



Description. — Top of head, nape, and median dorsal region the 

 usual mixture of black and pale ochraceous buff, becoming clearer 

 ochraceous buff on the sides where there is but slight admixture of 

 black hairs. Compared with fiavipcs the ochraceous tint is brighter, 

 but not so bright as in momhasae in which the head and nape are nearly 

 clear, instead of being largely mixed with black. Fore and hind feet 

 covered with short white hair. Area between the eye and ear paler, 

 lower border of eye black. Ventral surface of head and body pure 

 white to the roots of the hairs. Upper surface of tail thinly clothed 

 with coarse, short, black hairs, not appreciably longer at the tip; 



