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 njA inches, female io>^ inches; 
length of hind foot from the hock to the tips of the hoof, 
male 17^ inches, female, 16inches; length of ear from 
notch, male 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 6 *j 4 > inches. The 
widest-spread female horns show a width of 11^2 inches and 
