BY CAPTAIN F. W. HUTTON. 43 



America and Austi'alasia, for in that case there would have been 

 a far greater commingling of the land faunae and floras. It is 

 the origin of the first and third elements which has given rise to 

 such difl^erences of opinion. These are developed far more 

 strongly in Australia and Tasmania than in New Zealand; and 

 the explanation of the third will probably explain the first also. 

 I will, therefore, briefly review the three hypotheses (variously 

 modified) which have been proposed. 



1. The first explanation is that the different groups of animals 

 and plants in question have migrated from the northern hemisphere 

 into the southern by the present continents and have since then 

 become extinct in the north. With regard to the South African 

 connection, this explanation will be readily accepted. The fact 

 that Proteaceous plants -now almost confined to S. Africa and 

 Australia — wei'e formerly abundant in Arctog«a is a proof, so far 

 as they are concei'ned; and we may accept the same explanation 

 for the occurrence of the Baobab-tree ( Adansonia) in W. Australia 

 and the Fern-bird (Sphenmacus) in New Zealand. This theory 

 also explains the occurrence of the curious genus of wingless 

 locusts — Anostostoma — in Madagascar and Australia and the 

 connection of some birds of Madagascar and the Mascarene 

 Islands with others of New Zealand and Polynesia. It will also 

 explain the abundance of parrots in Australia and S. America, for 

 these lived in Europe in the Miocene period, as well as the 

 occurrence of tapirs and trogons in Central America and Malaya- 

 for these, like the large carnivora, must have passed from one 

 continent to the other by a northerly passage. Probably also it 

 will explain the relation of the curassows of S. America to the 

 megapodes of Australia and Polynesia, and the connection 

 between the lower passerine birds of both continents, as these 

 relationships are all very distant. 



But, however this may be, there are certain facts of distribution 

 which this theory cannot solve. A typical case is the distribu- 

 tion of the tree-frogs belonging to the genus Hyla. This contains 

 83 species in S. America, 28 in Australia, 17 in N. America, and 

 one each in India, China, and Europe; while Hylella is found 



