170 STUDIES IN LIFE AND SENSE. 



in the regulation of life and its distribution, we may lastly glance 

 at the history of that peculiar race of quadrupeds, the Marsupials, 

 or " pouched " mammals, in their relations to Australia as their 

 headquarters and home. These animals, possessing the kangaroo 

 as their most familiar representative, are, with one exception, con- 

 fined to Australia, along with certain other and lower quadrupeds, 

 such as the Ornithorhynchiis and Echidna. The exception to 

 the rule that the two lowest orders of quadrupeds are confined to 

 the Australian region is the opossum family {Didelphid(Z\ which 

 occurs in the New World. Bearing in mind the facts that, firstly, 

 save a few recently introduced bats and a rodent or two, Australia 

 has no native mammals of higher grade ; that, secondly, the kan- 

 garoo and its neighbours represent in that land the fulness of quad- 

 ruped life elsewhere; and that, thirdly, save the opossums, those 

 animals are absolutely confined to Australia, how, it may be asked, 

 are these peculiarities to be accounted for? If the theory of 

 special creation be appealed to, it would find it necessary to insist, in 

 virtue of its own terms, that the marsupials were created where we 

 now find them. Such a theory, however, supplies no intellectual 

 reason why the opossum, a typical enough marsupial, should have 

 been created in the New World, and thus have been left mysteriously 

 and arbitrarily outside the limits of the Marsupial or Australian 

 territory. Let us endeavour to ascertain what explanation of these 

 apparently anomalous facts the science of distribution can afford. 



Firstly, from the geological side comes the evidence that Australia 

 has never possessed, at any time, any native quadrupeds of higher 

 type. All the fossil remains of the Tertiary and Post-Tertiary age 

 discovered in Australia are those of Marsupials, often of giant size, 

 but still allied to the existing quadrupeds of the region. But geology 

 opens up a new vista of thought before us when it reveals the fact 

 that in the earliest Tertiary period Marsupials occurred in Europe, 

 these being the remains of opossums. In older deposits that is, in 

 the Oolite and Trias of Europe, occur the remains of Marsupials, 

 some of which are well-nigh identical with the little banded ant-eater 

 (Myrmecobius] occurring in the Australia of to-day. Passing to 

 North America, we discover in the Triassic rocks of that continent 

 the Dromatherium, likewise an ally of the living ant-eater of Australia. 

 So far, therefore, from Marsupials having mysteriously sprung into 

 being in Australia, we discover that in Triassic times they existed not 

 only in Europe but in North America, and that, in fact, they may be 

 regarded as having possessed a wide Palaearctic range in that period 

 and in its succeeding Oolitic epoch likewise. 



Let us note, again, that the marsupial and allied quadrupeds resem- 

 bling the ornithorhynchus were the oldest and earliest in time, as well 

 as the lowest in structure. The problem of the origin of the Australian 



