686 THE POPULAR SCIENCE MONTHLY. 



ou tangs, wild boars, deer, elephants, and squirrels, like those which 

 now people Borneo, instead of, or side by side with, the kanga- 

 roos, wombats, and other marsupials, which, as we know, actually 

 form the sole indigenous mammalian population of Greater Brit- 

 ain beneath the Southern Cross. Of course, in the end, the mys- 

 terious and tremendous Captain Lawson proved to be a myth, an 

 airy nothing, upon whom imagination had bestowed a local habi- 

 tation (in New Guinea) and a name (not to be found in the army 

 list). Wallace's Line was saved from reproach, and the intrusive 

 rhinoceros was banished without appeal from the soil of Papua. 



After the deep belt of open sea was thus established between 

 the bigger Australian continent and the Malayan region, how- 

 ever, the mammals of the great mainlands continued to develop 

 on their own account, in accordance with the strictest Darwinian 

 principles, among the wider plains of their own habitats. The 

 competition there was fiercer and more general ; the struggle for 

 life was bloodier and more arduous. Hence, while the old-fash- 

 ioned marsupials continued to survive and to evolve slowly along 

 their own lines in their own restricted southern world, their col- 

 lateral descendants in Europe, and Asia, and America, or else- 

 where, went on progressing into far higher, stronger, and better 

 adapted forms — the great central mammalian fauna. In place of 

 the petty phalangers and pouched ant-eaters of the oolitic period, 

 our tertiary strata in the larger continents show us a rapid and 

 extraordinary development of the mammalian race into monstrous 

 creatures, some of them now quite extinct, and some still holding 

 their own undisturbed in India, Africa, and the American prairies. 

 The paleotherium and the dinoceras, the mastodon and the mam- 

 moth, the huge giraffes and antelopes of sunnier times, succeed to 

 the ancestral kangaroos and wombats of the Secondary strata. 

 Slowly the horses grow more horse-like, the shadowy camel begins 

 to camelize himself, the buffaloes acquire the rudiments of horns, 

 the deer branch out by tentative steps into still more complicated 

 and more complicated antlers. Side by side with this wonderful 

 outgrowth of the mammalian type, in the first plasticity of its vig- 

 orous youth, the older marsupials die away one by one in the ge- 

 ological record before the faces of their more successful competi- 

 tors ; the new carnivores devour them wholesale, the new rumi- 

 nants eat up their pastures, the new rodents outwit them in the 

 modernized forests. At last the pouched creatures all disappear 

 utterly from all the world, save only Australia, with the solitary 

 exception of a single advanced marsupial family, the familiar 

 opossum of plantation melodies. And the history of the opossum 

 himself is so very singular that it almost deserves to receive the 

 polite attention of a separate paragraph for its own proper eluci- 

 dation. 



