1900 - 1 .] Mr F. H. A. Marshall on Hear in the Equidce. 383 
A longitudinal streak is commonly very distinct, and is often 
brought about by the presence of pigment on one side of the hair 
but not on the other. The medulla is wanting in the tip and root 
regions as in the Burchell zebra hairs. The hairs, including those 
of the mane, undergo a marked flattening. This is remarkable, 
seeing that sections through mane hairs, not only of the Burchell’s 
but also of the Somali zebra, are nearly, if not quite circular, even 
those through the hair in the middle of its length where the 
degree of flattening is often greatest. The sections also show that 
the pigment is not specially aggregated towards the medulla, but 
is spread fairly evenly through the cortex, except in cases where 
the hair is longitudinally striped by pigment being present in much 
greater quantity on one side of the medulla than on the other. 
The line of demarcation between the cortex and medulla is parallel 
to the surface of the hair and not irregular as in the Burchell’s 
zebra. Fig. 8 represents a section through a mane hair from a 
common zebra. 
A study of the hairs of the Somali or Grevy’s zebra leads to the 
conclusion that this zebra stands apart from all the others. 
Nathusius has commented on the extreme shortness of the hairs 
of the side of the body, their average length being about 5 mm. 
The breadths of the hair and of the cortex on one side, taken as 
before in three places, are as follows : — 
Breadth of cortex on one side Breadth of hair in 
of medulla in three places. three places. 
These measurements show considerable divergence from those of 
the other zebra hairs, and what is more, they are remarkably 
constant, being approximately the same for any fully grown hair 
drawn from the side of the body. The medulla is absent for some 
distance from the root, and where it makes its appearance is 
accompanied by a sudden thickening of the hair. Thus the hairs 
have long medullaless stalks. The pigment, which is thick in the 
greater part of the hair’s length, becomes thinner passing along the 
Equns Grevyi. 
(1) -0162 mm. 
(2) *0162 mm. 
(3) *0216 mm. 
•108 mm. 
‘162 mm. 
•063 mm. 
