WALLABIES. 
245 
at the tip, 24 inches. The remaining four species are all smaller; the north¬ 
western short-eared rock-wallaby (P. brachyotis ) being distinguished by the 
character from which it takes its name. The whole of the rock-wallabies are 
confined to continental Australia, and, as their name implies, frequent rocky 
districts, whereas the true wallabies are plain-dwelling animals. Their tails lack 
the stiffness of those of the latter, and appear to be used rather in balancing the 
body when leaping, than as a third support. The brush-tailed rock-wallaby, 
YELLOW-FOOTED EOCK-WALLABY liat. size). 
according to Gould, collects in large flocks, and forms regular well-beaten tracks 
on the mountain-sides. 
spur-tailed Three species of wallaby differ from all other mammals, with 
wallabies. the single exception of the lion, in having the extreme tip of the tail 
furnished with a horny spur or nail, the use of which is at present unknown. 
They are further distinguished by the hairy muzzle, by the length and narrowness 
of the fourth toe of the hind-foot, and by the length of the tapering tail, on which 
the hair is short. The upper incisor teeth are relatively small, and decrease in size 
from the first to the third. They are all of moderate or small size, with short hair, 
and are some of the most graceful members of the family. The nail-tailed wallaby 
(Onychogale ungaifera ) is of a general fawn-colour, and distinguished by the great 
length of the tail, and the large size of its terminal nail; the length of the head 
and body being 26 inches, and that of the tail an inch more. It is a rare species 
