ON ZHBRA-HORSH HYBRIDS. 65 
measured without offering any resistance. At birth Norna 
generally resembled Romulus, both in colouring, markings, and 
shape; but her head was relatively smaller, and the ears rela- 
tively shorter. There was, however, a very important and 
interesting difference between Norna and the other hybrids. As 
already pointed out, the croup and rump of Romulus were at the 
outset marked by numerous rows of spots having on the whole a 
transverse direction. When his new coat was completed, in 
August last, I noticed that many of the spots had united to form 
somewhat zigzag bands that in their direction agreed closely 
with the stripes on the hind quarters of the Somali Zebra. In 
Norna, instead of spots over the hind quarters, there were from 
the first numerous narrow and hardly at all wavy stripes, which 
line for line almost agreed with the markings in the Somali Zebra, 
But, further, many of these all but transverse stripes reached, 
or all but reached, a stripe running obliquely across the hind 
quarters in almost the same position as the oblique stripe in the 
Somali Zebra which I have elsewhere referred to as the upper 
femoral stripe. The remarkable difference between the markings 
over the hind quarters of Norna and her sire Matopo, and the 
equally remarkable resemblance between these markings in Norna 
and the Somali Zebra, seem to me to throw a flood of light on the 
relationships of the stripes in the various species and varieties 
of Gebras, and at the same time strongly to support the view 
already advanced, that the difference between the stripes of the 
sire and his various hybrid offspring is in all probability due to 
atavism or reversion.* If this is the correct explanation, it 
follows as a matter of course that at least in the markings the 
Somali is the most primitive of all the known recent ZGebras. 
That the hybrids have reverted in at least their markings 
towards a somewhat remote ancestor—it may be a common 
ancestor of both the Horses and Zebras—is also indicated by 
the presence of faint ‘“‘shadow” stripes on the neck. From 
Matopo having twelve cervical stripes and some Zebras having 
in addition nine or ten “‘shadow”’ stripes, and from Romulus 
having twice as many stripes as Matopo, it may be inferred the 
typical number of cervical stripes in Zebras is twenty-four or 
thereabout. But in Norna, in addition to the twenty-four 
* See the ‘ Veterinarian,’ December, 1897. 
4ool. 4th ser. vol. II., February, 1898, F 
