Chap. V. 
LAWS OF VAKIATION. 
163 
here, as before, I lie under a great disadvantage in 
not being able to give them. I can only repeat that 
such cases certainly do occur, and seem to me very 
remarkable. 
I will, however, give one curious and complex case, 
not indeed as affecting any important character, but 
from occurring in several species of the same genus, 
partly under domestication and partly under nature. 
It is a case apparently of reversion. The ass not rarely 
has very distinct transverse bars on its legs, like those 
on the legs of the zebra: it has been asserted that these 
are plainest in the foal, and from inquiries which I have 
made, I believe this to be true. It has also been as- 
serted that the stripe on each shoulder is sometimes 
double. The shoulder-stripe is certainly very variable 
in length and outline. A white ass, but not an albino, 
has been described without either spinal or shoulder 
stripe; and these stripes are sometimes very obscure, or 
actually quite lost, in dark-coloured asses. The koulan 
of Pallas is said to have been seen with a double shoulder- 
stripe. The hemionus has no shoulder-stripe ; but traces 
of it, as stated by Mr. Blyth and others, occasionally 
appear: and I have been informed by Colonel Poole 
that the foals of this species are generally striped on 
the legs, and faintly on the shoulder. The quagga, 
though so plainly barred like a zebra over the body, is 
without bars on the legs; but Dr. Cray has figured 
one specimen with very distinct zebra-like bars on the 
hocks. 
With respect to the horse, I have collected cases in 
England of the spinal stripe in horses of the most dis¬ 
tinct breeds, and of all colours; transverse bars on the 
legs are not rare in duns, mouse-duns, and in one 
instance in a chestnut: a faint shoulder-stripe may 
sometimes be seen in duns, and I have seen a trace in a 
