THE AUSTRALIAN GREAT BARRIER REEF. 133 



The facts above related infallibly demonstrate that the countries of New Guinea and North 

 Queensland were in former times connected. The very conspicuous racial distinctions between 

 the human inhabitants of New Guinea, the Torres Strait Islands, and the Australian con- 

 tinent, indicate, notwithstanding the near affinities of the lower mammalia, that the separation 

 of the districts must have been accomplished in prehistoric times, probably in a middle tertiary 

 epoch. This separation, moreover, could not have been effected by any other telluric move- 

 ment than that of subsidence, and this, as shown by the Admiralty charts, to an extent of at 

 least six or seven fathoms. The restoration of the land to a higher level, by the few fathoms 

 required to indicate the former continuity of New Guinea with Cape York Peninsula, would 

 have the effect of reducing the depth of the lagoon, or Inner Route Channel, between the 

 Barrier and the mainland from Cape Flattery northwards, to such an extent that this route 

 would, in many portions of its course, be virtually impracticable. In the southern moiety of 

 its area, where the large rivers previously mentioned join the sea, the depth of the water is 

 so much greater, twenty to thirty fathoms and over, that the existing route would not be 

 materially affected, while the mouths of the rivers would not be brought much nearer to 

 the outer edge of the Barrier. 



Repairing to the southern extremity of the Australian continent, we find a large detached 

 island, Tasmania, or Van Diemen's Land, of inconsiderable size as seen in the general map 

 of Australia, but actually as large as Ireland. This island is separated from the Australian 

 mainland by Bass's Strait, having a width of one hundred and fift}' miles, and a minimum depth 

 of about forty fathoms. An examination of the fauna of Tasmania reveals the fact that it, 

 too, notwithstanding its present isolated position, must in an historically ancient, but geologi- 

 cally comparatively recent, period, have formed an integral portion of the Australian mainland. 

 The longer period that must have elapsed since the separation of Tasmania, as compared with 

 New Guinea, from Australia, is a natural corollary of the greater depth of the intervening 

 channel, and is supported by the following evidence concerning the present and the past con- 

 ditions of the island and the continental faunas. 



It is particularly noteworthy that the two unique carnivorous marsupials known as the 

 Tasmanian Tiger or Wolf, Thylacimis cynocephaliis, and the Tasmanian Devil, Sarcophilns itrsiiius, 

 are found living at the present day only in the Island of Tasmania. Remains of animals 

 generically identical with both of these types, but representing larger and more formidable 

 species, occur as Pleistocene fossils on the Australian mainland. The majority of the mar- 

 supial forms are, however, still common to both the continental and the island faunas, or are 

 represented by closely allied species. The ordinary (or Great) Kangaroo, Macropns major ; 

 the common Opossum, or Vulpine Phalanger, Trichosunis vulpcciilo ; the Ring-tailed Opossums 

 Pseudochiriis Cooki ; the Wallaby, Macropns nificollis ; and the Native Cat, Dasynrus viverrinns, 

 are all represented both in Tasmania and on the mainland. Neither is there any substantial 



