684 '^HE POPULAR SCIENCE MONTHLY. 



the very oldest mammalian families, and therefore, I need hardly 

 say, in the leveling and topsy-turvy view of evolutionary biology, 

 the least entitled to consideration or respect from rational observ- 

 ers. For of course in the kingdom of science the last shall be first, 

 and the first last ; it is the oldest families that are accounted the 

 worst, while the best families mean always the newest. Now, the 

 earliest mammals to appear on earth were creatures of distinctly 

 marsupial type. As long ago as the time when the red marl of 

 Devonshire and the blue lias of Lyme Regis were laid down on 

 the bed of the muddy sea that once covered the surface of Dorset 

 and the English Channel, a little creature like the kangaroo rats 

 of Southern Australia lived among the plains of what is now the 

 south of England. In the ages succeeding the deposition of the 

 red marl, Europe seems to have been broken up into an archi- 

 pelago of coral reefs and atolls ; and the islands of this ancient 

 oolitic ocean were tenanted by numbers of tiny ancestral marsu- 

 pials, some of which approached in appearance the pouched ant- 

 eaters of Western Australia, while others resembled rather the 

 phalangers and wombats, or turned into excellent imitation car- 

 nivores, like our modern friend the Tasmanian devil. Up . to the 

 end of the time when the chalk deposits of Surrey, Kent, and Sus- 

 sex were laid down, indeed, there is no evidence of the existence 

 anywhere in the world of any mammals differing in type from 

 those which now inhabit Australia. In other words, so far as re- 

 gards mammalian life, the whole of the world had then already 

 reached pretty nearly the same point of evolution that poor Aus- 

 tralia still sticks at. 



About the beginning of the Tertiary period, however, just after 

 the chalk was all deposited, and just before the comparatively 

 modern clays and sandstones of the London basin began to be laid 

 down, an arm of the sea broke up the connection which once sub- 

 sisted between Australia and the rest of the world, probably by a 

 land-bridge, via Java, Sumatra, the Malay Peninsula, and Asia 

 generally. " But how do you know," asks the candid inquirer, 

 " that such a connection ever existed at all ? " Simply thus, most 

 laudable investigator — because there are large land mammals in 

 Australia. Now, large land mammals do not swim across a broad 

 ocean. There are none in New Zealand, none in the Azores, none 

 in Fiji, none in Tahiti, none in Madeira, none in Teneriffe — none, 

 in short, in any oceanic island which never at any time formed 

 part of a great continent. How could there be, indeed ? The 

 mammals must necessarily have got there from somewhere ; and 

 whenever we find islands like Britain, or Japan, or Newfoundland, 

 or Sicily, possessing large and abundant indigenous quadrupeds 

 of the same general type as adjacent continents, we see at once 

 that the island must formerly have been a mere peninsula, like 



