382 
Proceedings of Royal Society of Edinburgh. [sess. 
(2) is taken in the middle of the hair-shaft, half-way between the 
point and the root; (1) is taken half-way between the point and 
(2) ; and (3) is taken half-way between the root and (2). A 
longitudinal streak, formed by pigment darker coloured than that 
colouring the rest of the cortex, may not infrequently be observed, 
so that the hair may appear, if mounted in a suitable position, 
differently coloured on one side of the cortex to what it is on the 
other. The medulla in many hairs is broken down in places and 
may be absent from the root for a distance as much as a quarter 
the length of the hair. The latter may reach 20 mm. Sections 
through the hairs of the mane which is upright are circular. 
Fig. 7 represents such a section. The line of demarcation between 
the cortex and medulla is irregular. The pigment is seen to be 
distributed much more thickly in that part of the cortex nearest the 
medulla than towards the periphery of the hair. The hairs here 
described are those of the Chapman’s variety of the Equus 
Burchelli. This animal is regarded by JNathusius as a distinct 
species, as is also Equus Bohmi. 
Equus quagga. 
This animal, though undoubtedly a member of the Burchell’s 
group of zebras, is commonly regarded as a distinct species. The 
hair characters are closely similar to those of the Chapman’s zebra, 
but those of the side of the body tend to be longer and may reach 
25 mm. in length ; that is longer than the same hairs in any of 
the other zebras. 
Equus zebra. 
The shoulder hairs of the common or mountain zebra are not 
strikingly different to those of the Burchell’s. The length is about 
the same. The following are measurements taken as with the 
Burchell’s zebra hairs of the breadth of a typical shoulder hair 
and of the breadth of the cortex on one side of the same hair : — 
Breadth of cortex on one side Breadth of hair in 
of medulla in three places. three places. 
(1) ’0144 mm. -081 mm. 
(2) ’0162 mm. *090 mm. 
(3) ‘0162 mm. -063 mm. 
