MAMMALS COLLECTED ON THE ORANGE RIVER. 493 



mostly slaty ; in the type of nigricauda they are slaty laterally, 

 white-based centrally, and in kalaharicus and the Mossamedes 

 species {nitela^ see below) they are wholly white. Face grey, but 

 the brown of the crown reaches as far forward as between the eyes. 

 Dark facial markings scarcely developed at all, the darker edges of 

 the orbit quite naiTow and inconspicuous, and not extending 

 forwaids or backwards as an ocular streak. Ears about of the 

 colour of the head ; hairs behind them huffy brown. Hands and 

 feet white, with darker patches on the metapodials. Tail long, 

 black, scarcely so thickly hairy as in nigricauda. 



8kull with well-marked supraorbital ridges, long palatal fora- 

 mina, and rather small bullae, much smaller than in kalaharicus, 

 rather smaller than in nitela, those of nigricauda not known. 



Dimensions of the type, measured in the flesh : — 



Head and body 150 mm. ; tail 189 ; hind foot 29 ; ear 22. 



Skull : greatest length 35"5 ; condylo-incisive length 34 ; zygo- 

 matic breadth 185 ; interorbita.l breadth 5 ; palatal foramina 86 ; 

 bullno G'9 ; upper molar series (worn) 5'G. 



Type. Old female. B.M.. No. 23. 5.9.156. Original number 

 180.' Collected 2 December, 1922. 



This species is distinguishable from T. nigricauda by its slaty- 

 based belly hairs, its larger feet, and the marked reduction in the 

 development of the black facial markings. 



Oapt. Shortridge made special mention of this striking species 

 as being quite new to him, and we have much pleasure in naming 

 it in his honour. 



[In working out Thallomys shortridgei we have found that the 

 genus would appear to contain six species, which might be 

 arranged as follows : — 



A. Black jEliomi/s-\ike face markings strongly 



developed. 



a. Bulla) comparatively small, about 7 mm. in 



length. Angola 1. T. nitela, B]p. n. 



b. Bulltii large, over 8 mm. in length. East 



Africa 2. T. loringi HcW. 



B. Black face markings less developed. 



c. Face markings medium. 



a^. Hairs of chest wholly wliite, of belly 



slaty at base. Namaqualaud 3. T.longicaudaThoi. 



6^. Hairs of whole underside white to 



base. Kalahari 4, T. kalaharicus DoWm. 



d. Pace markings practically absent. 



c^. Belly hairs slaty based. Orange Kiver. 5. T. shortridgei T. & H. 

 d^. Belly hairs white at base. E. Africa. 0. T, sootti, sp. n. 



The teeth of all are of about the same size — 5*6-5*9 for tlie 

 upper series — with the excei)tion of T. longicauda, in which this 

 measurement is only about 5' 1 mm. 



Details of the new species : — 



T. nitela, sp. n. 



Size comparatively large. Central dorsal area huffy brown. 

 Sides and flanks markedly greyer. Under surface white, the hairs 

 white to their bases. Forehead grey. A strong black facial line 

 running from the side of the muzzle through the eye nearly to 



