104 ANALOGOUS TYPES. 
animals resemble ours so closely that the Eng- 
lish settlers have called many of them by the 
same names, there are no genuine Wolves, Foxes, 
Sloths, Bears, Weasels, Martens, Squirrels, or 
Rats in Australia. The Australian Mammalia 
are peculiar to the region where they are found, 
and are all linked together by two remarkable 
structural features which distinguish them from 
all other Mammalia and unite them under one 
head as the so-called Marsupials. They bring 
forth their young in an imperfect condition, and 
transfer them to a pouch, where they remain 
attached to the teats of the mother till their 
development is as far advanced as that of other 
Mammalia at the time of their birth ; and they 
are further characterized by an absence of that 
combination of transverse fibres forming the large 
bridge which unites the two hemispheres of the 
brain in all the other members of their’ class. 
Here, then, is a series of animals parallel with 
ours, separated from them by anatomical fea- 
tures, but so united with them by form and ex- 
ternal features that many among them have been 
at first associated together. 
Cuvier has already alluded to this, when he 
speaks of subordination of characters, distinguish- 
ing between those controlling the whole organ- 
ization and those that play only a secondary 
part in it. The skill of the naturalist consists 
