THE CARBONIFEROUS PERIOD. 
80 
Shark lias features which were very character- 
istic of the Carboniferous Sharks and are lost in 
the modern ones, so that it affords us a sort of 
link, as it were, and a measure of comparison, 
between those now living and the more ancient 
forms. It is an interesting fact that this only 
living representative of the Carboniferous Shark 
should be found in New Holland, because it is 
there, in that isolated continent, left apart, as it 
would seem, for a special purpose, that we find 
reproduced for us most fully the character of the 
Animal Kingdom in earlier creations. 
The first Mammalia in the world were pouched 
animals, having that extraordinary attachment 
to the mother after birth which characterizes the 
Kangaroo. In New Holland almost all the Mam 
malia are pouched, and have also the imperfect 
organization of the brain, as compared with the 
other Mammalia, which accompanies that pecu- 
liar structural feature ; and although the Amer- 
ican Opossum makes an exception to the rule, 
it is nevertheless true that this type of the Ani- 
mal Kingdom is now confined almost exclusively 
to New Holland. Whether this living picture of 
old creations in modern garb was meant to be 
educational for man or not, it is at least well 
that we should take advantage of it in learning 
all it has to teach us of the relations between the 
organic world of past and present times. 
