1900-1.] Mr F. H. A. Marshall on Hair in the Equidee. 381 
Sir Harry Johnston has more recently obtained a complete skin and 
two skulls of the animal, and these show that it is related to the 
extinct Helladotherium and may perhaps he referred to that genus.* 
Dr Ridewood, at a more recent meeting of the Zoological Society, 
exhibited microscopic preparations of the hairs of this animal and 
also of giraffe and antelope hairs, and pointed out that the hairs of 
the so-called Equus Johnstoni, while they differed from those of 
antelopes, resembled those of the giraffe and also those of the 
zebra. 
The genus Equus contains some ten or more species, including 
two species of horses, three or four of asses, and a doubtful number of 
species of zebras. Three species of zebras are, however, well defined, 
namely, the Burchell’s zebra {Equus Burchelli ), the common or 
mountain zebra {Equus zebra) and the Somali or Grevy’s zebra 
{Equus Grevyi), the skins of which are figured in Plates I., II. and III. 
Some account will now be given of the hairs of these zebras, after 
which the hairs of the horse will be referred to, and the paper will 
be concluded by a description of the hairs of certain zebra-horse 
hybrids and a reference to the telegony hypothesis. 
Equus Burchelli. 
In this, as in other zebras, the hairs are generally of stouter 
form than in the horse or ass, and the medulla in the case of the 
shoulder hairs at any rate is relatively thicker in the former than 
in the latter. The exact measurements for a typical hair from the 
shoulder region of the Burchell’s zebra are as follows : — - 
Breadth of cortex on one side 
of medulla in three places. 
(1) *018 mm. 
(2) *018 mm. 
(3) -027 mm. 
Total breadth of hair in 
three places. 
•099 mm. 
*189 mm. 
•072 mm. 
are about 5 mm. in length, or about the length of the shoulder and side hairs 
in the Somali and Penrice’s zebra, from both of which they differ in shape, 
tapering to a point much more gradually. In the relative development of 
the medulla and cortex they closely resemble equine hairs, differing entirely 
from the hairs of antelopes, goats, and deer. 
* Since the above was written Professor Lankester has named this animal, 
which is called the Okapi, Ocapia Johnstoni, Dr Sclater having already 
supplied the specific name. 
