THE GAZELLES AND THEIR ALLIES 589 



to the Amala River and Loita Plains district of British 

 East Africa. Confined to the Nile drainage except at its 

 extreme northeast limits on the Loita Plains, where it 

 enters the Rift Valley system. South of this point and 

 lower down the Rift Valley it meets or merges into the 

 highland race of British East Africa, roosevelti. 



The Roberts race of the Grant gazelle was described by 

 Oldfield Thomas from specimens collected by F. Russel 

 Roberts and Gilbert Blaine in the vicinity of Mwanza, a 

 lake port on the southern coast of the Victoria Nyanza. 

 Ten years previous to this discovery Oscar Neumann had 

 collected specimens of the same race on the Loita Plains 

 of British East Africa and had noted their peculiar horn 

 shape, but had regarded them as abnormal specimens of 

 the typical race. In characters this race is distinguishable 

 from the other races chiefly by the peculiar wide-spread 

 horns which turn outward and diverge widely, the extreme 

 tips turning backward. Normally the spread equals the 

 length of horn taken along the curve, but in abnormally 

 twisted horns the spread greatly exceeds the length. The 

 females do not show the peculiar horn characters, but are 

 distinguishable by their almost total loss of the dark flank 

 band which is either obsolete or only faintly indicated pos- 

 teriorly. Both sexes differ further from their nearest ally, 

 roosevelti, by their lighter dorsal coloration. 



In size this race is practically equal to roosevelti. An 

 average specimen measures: in length of head and body 

 along the curve of the back, male 59 inches, female 53 

 inches; length of tail, male ii^^ inches, female io}4 inches; 

 length of hind foot from the hock to the tips of the hoof, 

 male 17^ inches, female, 16^ inches; length of ear from 

 notch, male 6^ inches, female 6% inches. The length of 

 the horns along the curve in the record male, a specimen 

 shot by R. J. Cuninghame on the Loita Plains and now in 

 the United States National Museum, is 28^ inches, and the 

 greatest spread at the tips is 39^ inches (record). The 

 second longest-horned male in the same institution is very 

 little above the average, measuring in length 25 inches and 

 in spread 25^^ inches. The longest-horned female has horns 

 15 inches in length with a spread of only Gj/i inches. The 

 widest-spread female horns show a width of 11^ inches and 



