Mamm lis from British East Afrlci. 523 



effect produced beiug that of areddish-brovvu tail, and not o£ 

 a black one. 



Skull a great deal smaller than that of nigricauda, shorter 

 and narrower ; markedly shorter nasals and narrower brain- 

 case. Auditory bullae much smaller and shorter. 



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



Head and body 164- mm. ; tail 208 ; hind foot 40-5 ; ear 22. 



Skull : greatest length 48 ; basilar length 36"8; condylo- 

 iucisive length 42; zygomatic breadth 24"7 ; interorbital 

 breadth 86 ; breadth of brain-case (across squamosal 

 region) 17"5; length of nasals 20'5 ; palatilar length 21"5 ; 

 width of palate (inside m^) 4'3 ; length of palatal foramina 9 ; 

 greatest diameter of bullse 12*5 ; alveolar length of upper 

 cheek-teeth 7'2, 



Hab. Nyama Nyango, Eusso Nyiro. Altitude 3000 feet. 



Type. Old male. Original number 1798. Collected on 

 January 27th, 1911. 



The much smaller size of the skull and lighter-coloured 

 tail are the chief points therein this new form differs from 

 the Mombasa species. I have taken as representing T. nigri- 

 cauda a long series of s[)ecimens recently obtained by 

 Mr. Kemp at Yoi and Taveta. The following are the cranial 

 dimensions of an adult male : — 



Greatest length 51 mm.; basilar length 40; condylo- 

 incisive length 45*3 ; zygomatic breadth 26*8 ; interorbital 

 breadth 9; breadth of brain-case (across squamosal region) 20 ; 

 length of nasals 23 ; p.ilatilar length 236 ; length of palatal 

 foramina 10; greatest diameter of bullae 14; alveolar length 

 of upper cheek-teeth 7'5. 



Tatera varia, described by Heller fx'om the Eusso Nyiro 

 River^ Sotik District, would appear to be the only other 

 member of the genus described from this district. T. varia 

 belongs to the fallax group with the white-tipped tails, and 

 is in no way related to nigricauda or the form here described. 



Otomys irroratus elgonis, Wrought. 



S. 1523, 1526, 1527,1531,1567,1571,1582, 1583,1595, 

 1596, 1617, 1618, 1637, 1641, 1642,1655, 1663, 1668,1714, 

 1715 ; ? . 1522, 1572, 1597, 1658, 1710. Solai, Mt. Kenya. 



Otomys angoniensis elassodon, Osg. 



(?. 1312, 1315, 1316 ; ? . 1307, 1314. Nakuru. 



^ . 1421, 1423, 1438, 1448, 1450, 1457, 1478, 1481, 1502, 

 1514, 1506 ; ? . 1422, 1458, 1459, 1475, 1485, 1497, 1498, 

 1499, 1515, 1516, Rumruti, Laikipia Plateau, 



