THE WOMBATS. 123 
in the northern hemisphere by the Marmots and in South 
America by the Viscachas, both of which are members of the 
Rodentia. In this instance, indeed, the resemblance is not 
confined to similarity of habits, since the Wombats not only 
resemble Marmots (save for their rudimentary tails), but also 
simulate them to a great extent in the structure and arrange- 
ment of their teeth, more especially in the form and number of 
their incisors, and in the total absence of canines. They thus 
afford an excellent instance of that parallelism in development 
which we have already alluded to as occurring among totally 
Side View of the Teeth of Wombat, 
different groups of animals, in the case of those adapted to 
similar modes of life and living under similar surroundings. 
Such a parallelism is, however, wanting in the case of the 
Kangaroos and Wallabies, which may be regarded as represent- 
ing in the Australian economy of nature the Ruminants of the 
Old World, since there is no similarity in the structure of the 
members of the two groups. The same holds good with re- 
gard to the Phalangers, which may be regarded as the repre- 
sentatives in Australia of both the Squirrels, Lemurs, and 
Monkeys of other regions. That the Flying Phalangers, which 
represent the Flying Squirrels of the Oriental Region and Africa, 
