98 Messrs. M. A. C. Hiuton and P. S. Kershaw on 



Hamilton ; presented to the British Museum by the Wellcome 

 Research Laboratory. 



Description. — This is a medium-sized sober-hued species, 

 differiiio- externally from 2\ rohusta and its allies by having 

 no tuft to the tail and in its skull by the more nearly ortho- 

 dont incisors and truncated rostrum, the nasals ending almost 

 tiush with the anterior surfaces of the incisors instead of 

 projecting noticeably beyond them. 



Size medium (average of ten adults : head and body 

 138 mm. ; tail 155; hind foot 32). 



Tail clothed throughout with short stiff hairs (black or 

 tlark brown above, pure white below), which do not com- 

 pletely conceal the annulations on the upper suiface. At 

 the tip these hairs become a little longer and finer, projecting 

 for 2 to 3 mm. beyond the last vertebra ; but there is no 

 pencil or dorsal fringe as in rohusta or macropus. 



Colour of upper surface much duller than in the species 

 with fringed tails. Ground-colour near "clay-colour," much 

 darkened by black hair-tips on top of head and along mid- 

 dorsum ; gradually brightening on flanks to dull buff. 

 Underparts sharply contrasted, pure white. Feet and hands 

 white above. Tail dusky above, dirty white below. 



Skull. — With nearly orthodont, rather broad, shallowly 

 grooved upper incisors. Anterior blades of premaxilUe, 

 between incisors and nasals, little developed. Nasals rela- 

 tivel}- short, not projecting far in advance of anterior faces of 

 incisurs ; occipito-nasal and nasal lengths respectively equal 

 to 108-110 7o a"^ 43-45 °/o of condylo-incisive length ; in 

 rohusta the corresponding dimensions are equal to 114— 115 °/q 

 and 49-52 °/o* i3rain-case relatively narrow and deep. 



Dimensions of type and of uo. 94 (an old Si in pareutlieses) : — Head 

 and body 169 (168J mm. ; tail 175 (— ) ; hind foot (on skins) 31 (35) ; 

 ear 19 (21). 



Skull: condylo-incisive length 37 '2 (39'7); occipito-nasal length 41'1 

 (42-8); nasals 16-6 X 3-9 (17-8 X 3-8); zygomatic breadth 20-8 (— ); 

 interorbital breadth 6-1 (6-5) ; cranial width 16"8 (16"8) ; median occi- 

 pital depth 10-9 (ll-l) ; bulUc H'C X 6-8 (12x7); dental length 20-G (22) ; 

 molars (crowns) 6'3 (t)'4). 



Remarks. — One of us lately has been paying much atten- 

 tion to this difficult genus. In the countries bordering the 

 Nile and in East Africa Taterona shows a tendency to split 

 into two well-maiked groups. In one of these groups the 

 tail is fringed and the coloration usually bright or intense ; 

 and these external characters are correlated with protruding- 

 nasals, large premaxillary outgrowths, opisthodont incisors, 

 and small cheek-teeth. In the other the tail has no fringe 



