I 



Black-tailed Rat from South Africa. 545 



Size of boJv ami liinJ foot markedly smaller than in 

 nigricauda; tail rather sliorter. General colour of dorsal 

 surface pale grey, faintly tinged with yellowi.sh down the 

 middle of the back. Flanks pale greyish white with no butf- 

 coloured suffusion. Hairs of back pale slate-grey witli 

 yellowish-grey tips; interspersed are a number of rather 

 long dark brownish hairs^ but much less evitlent than in 

 nigricanda. Face and heatl pale grey, rather darker on the 

 posterior part of head. Ocular rings dark brownish black, 

 the general effect a good deal less marked than in iwjricauda 

 and with no suggestion of the dark markings spreading on 

 to the nose. Ears clothed with yellowish-buff hairs. Backs 

 of hands and feet white. Entire underparts white, ventral 

 t-urface rather less sharply marked off" from the flanks than 

 in ni(/ricauda ; hairs of belly white throughout. Tail similar 

 in colour, but hairs considerably shorter, especially on the 

 apical portion of the tail. 



Skull much smaller than that of nigricauda, with shorter 

 nasals and palatal foramina. Zygomatic breadth a great 

 deal less. Molar teeth rather smaller. Unfortunately the 

 only adult skulls of nigricauda in the Museum collection are 

 imperfect, and it is at present impossible to compare the 

 cranial regions of the two forms. 



Dimensions of the type (measured in the flesh) : — 

 Head and body 135 mm.; tail 161; hind foot 25; 

 ear 24*5. 



Skull : greatest length 33*2 ; basilar length 27 ; condylo- 

 incisive length 315 ; zygomatic breadth 17 ; interorbital 

 constriction 4"3 ; squamosal breadth of cranium 15; length 

 of nasals 12"2 ; palatilar length 14"1 ; length of palatal 

 foramina 7'4; length of upper molar series 5*7. 



JJab. Molopo River, South Africa. Altitude 3000 feet. 

 Type. Adult female. B.M. no. 10. 6. 3. 34. Original 

 number 11. Collected on April 25th, 1909, by Mr. R. B. 

 Woosnam and presented to the British Museum by the 

 Subscribers to the Lake Ngami Expedition. 



AVhile working out the mammals collected by Mr. Woos- 

 nam during the Kgami Expedition, I provisionally identified 

 the type of this new form as E. nigricauda, the type skull 

 of nigricauda being too broken to be of any use for com- 

 parative purposes. Since then, however, some further 

 specimens of nigricauda, collected by Dr. Ansorge in Mos- 

 sauiedes, have been acquired by the Museum, and it is at 

 once evident, on comparing the skull of the Molopa specimen 

 with an adult skull of nigricatidu, that the two forms are 

 quite distinct. The skins of the series from i\Jo3samcdes are 



