14 NATURAL HISTORY. [MAMMALIA 
trees. The remaining animals, which live on the ground, have slender 
tails, covered with scales or scattered hair, as the elephant mice, ( Ma - 
croscelides ,) which have very long noses like a trunk, and their hind legs 
long; they have the habits of jerboas, and are only found in Africa. 
The shrew mice ( Sorex) and their allied genera have nearly equal legs 
and conical muzzles. The water shrews ( Crocidura) have the sides 
of the feet fringed. The musk shrew (Myogale ) has the nose rather 
more elongate and produced, and the foetid shrew 7 s (Pachyura ) have a 
thick tail covered with scattered bristles. The bristly shrew ( Gymnura ) 
of Malacca has much the character of the shrew, but the back is co¬ 
vered with bristly hair, while the fur of the shrews and their allies is 
soft and velvet-like. The hedgehogs ( Erinaceus ) are easily known 
from the rest of these animals by their back being covered with rigid 
spines like a porcupine. The latter have the power of covering them¬ 
selves almost entirely with this spiny coat when they roll themselves 
up. The Tenrecs ( Centetes) differ from all the others in having small 
cutting teeth; they are covered with rather spiny bristles, but they do not 
roll themselves up like the hedgehogs. They sleep during the hot 
weather, and are confined to Madagascar, but have been naturalized in 
the Isle of France. 
The family of Kangaroos ( Macroplcll, Cases 23—30) are peculiar 
for their young being nursed in a marsupial pouch on the belly of 
the mother, which is supported by two peculiar bones attached to the 
pubis. The thumbs of the hind feet are often distinct, opposable, and 
clawless. 
The more typical kinds have two long shelving cutting teeth in the lower 
jaw, and six erect teeth in the upper. This division contains two groups ; 
the first ( Phalangistina , Cases 23 and 24) consisting of the animals which 
live on trees or bushes. They have the thumb of the hind feet well de¬ 
veloped and opposable, and the toes separate. Some have the skin of 
the body expanded to enable them to jump better from tree to tree ; they 
are easily distinguished by the form of their tail; thus in Acrobates it is 
pennated and flat; in Petaurus bushy and broad ; and in Petauristc. 
elongate and roundish. Those which have the sides of the body simple 
usually have a more or less prehensile tip to their tail; in the Cuscus 
this organ is elongate, scaly and rat-like; in the Hepoona hairy and 
tapering, and in the Phalangista it is cylindrical and hairy ; there are 
also differences in the number and form of the teeth. The Tarsipes has 
the index finger of the hind feet short, and the lower front teeth are 
very slender and transparent, and the other teeth very rudimentary 
The koala ( PhascolarctGS ) has the habit and appearance of the pre¬ 
ceding genera, but it is a more heavy animal, and has no tail; they live 
on trees, earning their young on the back of their neck. The second 
group ( Macropina , Cases 24—29) have the tarsus and the middle toes 
of the hind feet elongated, and the two inr^r ones rudimentary, equal, 
and united together. One of these, the tree kangaroo, ( Dendrolegus , ) 
which chiefly lives on trees, has the three outer toes of the hind feet 
nearly square, and armed with curved claws; the tail elongated and 
hairy, like squirrels. The rest of the animals of the group which live 
always on the ground have the three outer toes of the hind feet of un¬ 
equal length, the index toe being the longest. Their tails are conical 
and tapering, covered with rigid hair. Some, which have been included 
