SHEEP. 213 
triangular in section, and marked by parallel transverse wrinkles, while their colour 
is greenish or brownish; they are directed outwardly from the sides of the head, 
their upper border being at first always convex, and the curvature generally 
taking the form of an open spiral, with the tips turned outwards. The face has 
generally, but not always, a small gland below the eye, and there is a corresponding 
depression in the skull for its reception ; and the muzzle differs 
from that of the oxen in being pointed and covered with short 
hair. Another distinctive feature of the group is the presence of 
a small gland in each foot between the hoofs; and the females 
have but two teats in place of the four of the oxen. The males 
of all sheep are devoid of any strong odour; neither have they 
any beard on the chin. As a rule, in wild species, the tail is 
very short; but in one case it reaches just below the hocks. The 
ears are of moderate length; and the hair, in wild species, is short 
and stiff, although it may be elongated on the throat and fore- 
quarters. The upper molar teeth differ from those of the oxen 
in having narrow crowns without any additional column on the 
inner side. The feet have only the upper ends of the lateral 
metacarpal and metatarsal bones remaining. 
As regards the characters of their molar teeth, the sheep songs or THE LEFT 

resemble the gazelles, and it is accordingly not improbable that Cen ee 
. . Croc 
they may trace their descent to extinct antelopes more or less Dawkins. 
nearly allied to that group. Oxen, on the other hand, having 
molar teeth nearly similar to those of the sable antelope and oryx, may be more 
nearly allied to the ancestors of that group. 
Sheep are represented at the present day by eleven wild species, 
which are mostly inhabitants of Europe and Asia northwards of the 
outer range of the Himalaya; although one species occurs in the Punjab and Sind, 
a second in Northern Africa, and a third in North America. They associate 
either in parties of two or three individuals, or in flocks of considerable size ; and 
are essentially mountain animals. Very generally, however, sheep inhabit the more 
open mountain districts, rather than the craggy and steeply-scarped regions selected 
by the goats. 
Most of the species are very nearly related to one another, and in several 
instances it is difficult to determine whether certain forms ought to be regarded as 
Distribution. 
distinct species or merely as local races. Geologically, the sheep are even a more 
modern group than the oxen, none of them being definitely known to occur before 
the epoch of the so-called forest-bed of the Norfolk coast, which belongs to the upper 
part of the Pliocene or the lower part of the Pleistocene period. 
THE AMERICAN AND KAMSCHATKAN WILD SHEEP (Ovis canadensis 
and O. nivicola). 
The American wild sheep or “ bighorn ” (O. canadensis) and the Kamschatkan 
wild sheep (0. nivicola) are two very closely-allied species, differing in several 
important respects from the other members of the genus. The most distinctive 
