44 DISTRIBUTION OF SOUTHERN FAUNAS, 



only in Australia and tropical America. Again the fresh-water 

 tortoises belonging to the family Chelydida; are restricted to 

 Australia and S. America. The fresh water fish Osteoglossum is 

 represented by species in S. America, Queensland, and Borneo; 

 and the South American beetles are more closely related to those 

 of Australia and Africa than they are to those of N. America. 

 Indeed the connection between 8. America and Australia is .so 

 marked in the Buprestidcc and Longicornia that Mr. Wallace, 

 who as a general rule strongly supports the northern route, says 

 that " there must probably once have been some means of com- 

 munication between the two regions better adapted to these 

 insects than any they now possess." And as several of the 

 Eocene mammalia of Patagonia were closely allied to those now 

 living in Australia the evidence for a former land passage between 

 the two countries may be considered as conclusive. The northern 

 route therefoi'e fails to give a full and satisfactory account of the 

 whole of the facts, and we must look to some other route to 

 supplement it. The portions of the faunas unaccounted for are 

 all old forms of life, and consequently we must conclude that the 

 means of communication used by them has been long ago destroyed ; 

 for if not it would also have been used for modern groups. 



2. Turning now to the proposed southern route by an Antarctic 

 continent, it has this in its favour that, as the greater extension 

 of Antarctic land in the late Tertiary era has been allowed, it is 

 not difficult to suppose that at a still earlier time, that is in the 

 Mesozoic era, a large continent might have existed there. One 

 difficulty is in the climate. How could tropical, or sub-tropical, 

 snakes, insects, and fresh-water tortoises and fishes pass through 

 such high latitudes '? The example of Greenland is pointed to, 

 but in Greenland the climate indicated is temperate only, not 

 sub-tropical or tropical. Again it is stated, in explanation, that 

 there is evidence of a much warmer climate having obtained in 

 the southern hemisphere in Miocene times than now. But this 

 appears to have been a period of depression throughout southern 

 Australasia, and it does not follow that the climate would be 

 equally mild when an Antarctic continent existed. I do not 



