THE POUCHED MAMMALS. 237 
There are also a few species still living in America, but at 
the present day not a single marsupial animal lives on the © 
continent of Asia, Africa, or Europe. 
The name of pouched animals is given to the class on 
account of the purse-shaped pouch (marsupium) existing 
in most instances on the abdominal side of the female 
animals, in which the mother carries about her young 
for a considerable time after their birth. This pouch is 
supported by two characteristic marsupial bones, also 
existing in Cloacal animals, but not in Placental animals. 
The young Marsupial animal is born in a much more 
imperfect form than the young Placental animal, and only 
attains the same degree of development which the latter 
possesses directly at its birth, after it has developed in the 
pouch for some time. In the case of the giant kangaroo, 
which attains the height of a man, the newly born young 
one, which has been carried in the maternal womb not 
much longer than five weeks, is not more than an inch 
in length, and only attains its essential development 
subsequently, in the pouch of the mother, where it remains 
about nine months attached to the nipple of the mammary 
gland, 
The different divisions generally distinguished as families 
in the sub-class of Marsupial animals, deserve in reality 
the rank of independent orders, for they differ from one 
another in manifold differentiations of the jaw and limbs, in 
much the same manner, although not so sharply, as the 
various orders of Placental animals. In part they perfectly 
agree with the latter. It is evident that adaptation to 
similar conditions of life has effected entirely coincident or 
analogous transformations of the original fundamental form 
