THE DISTRIBUTION OF BRIGHT’S GAZELLE 73 
date and duration of the flight should also be recorded. These 
flights occur in other parts of the world, for Spence the botanist, 
whose journals were recently edited by Alfred Russel Wallace, 
and published under the title of * Notes of a Botanist on the 
Amazon ’ (Macmillan, 1909), records that between Para and 
Santarem, near the mouth of the Xinga, he saw vast multitudes 
of butterflies flying across the Amazon from N.N.W. to S.S.E. 
They were evidently in the last stage of fatigue ; some 
attained the shore, but a large proportion fell exhausted into 
the water. They were all of the common white and orange 
yellow species. The very slight wind there was blew from 
between E. and N.E. ; therefore the butterflies steered their 
course at right angles to it, and this was the case in subsequent 
flights he saw across the Amazon. But the most notable cir- 
cumstance is that the movement is always southwards, like 
the human waves which from earliest times seem to have 
surged one after the other over the whole length of America. 
Mr. Bates also records a flight of butterflies across the 
Amazon from N. to S. which lasted for two whole days without 
intermission except during the dark. These were nearly all 
a species of Callidryas, and the migrating horde was only 
composed of males. 
THE DISTRIBUTION OF BRIGHT’S GAZELLE 
The parts of British East Africa near the railway line, 
roughly between the spot at which the highland prairies are 
first reached and the Mau escarpment, form the principal 
habitat of Grant’s gazelle. Passing northwards to the Laikipia 
plains, one meets with a slightly different type, generally 
referred to as the northern form of Grant’s gazelle. The 
most noticeable difference in this type is in the shape of the 
horns, which are shorter than those of the typical Gazella 
granti , and are more like those of Peter’s gazelle. Nor do they 
curve backwards and forwards so much. Both these forms, as 
also Roberts’s variety, are almost always found on high, 
upland, well-grassed prairies. 
