G. M. Thomson. — On the Origin of the New Zealand Flora. 489 



tribution of the flora is not critically gone into, certain remarkable facts of 

 the distribution of genera such as Eucalyptus, Stilbocarpa, Metrosideros and 

 others, are brought forward by way of corroboration. 



Some four years after the publication of Professor Hutton's paper, Mr. 

 A, E. Wallace's great work on the " Geographical Distribution of Animals " 

 came out, in which due consideration is given to the question of the origin 

 of the New Zealand fauna, and to the discussion of Professor Hutton's views. 

 Mr. Wallace in this work does not agree with the idea that there was a 

 former great antarctic land connection, but believes that there was a great 

 southward extension of land, perhaps considerably beyond the Macquaries, 

 and that this being within the range of floating ice during the colder epochs, 

 and within easy reach of the antarctic continent during the warm periods, 

 there arose " that interchange of genera and species with South America, 

 which forms one of the characteristic features of the natural history of New 

 Zealand." Professor Hutton's theory is primarily based on the distribution 

 of the struthious birds, but Mr. Wallace is of opinion that the ancestral 

 struthious type probably once spread over the larger portion of the globe, 

 and that as higher forms, particularly of the Carnivora, became developed, it 

 was exterminated everywhere except in those regions where it was free from 

 their attacks, and that in these regions it developed into special forms 

 adapted to surrounding conditions. This conclusion is supported and 

 rendered almost certain by the discovery of remains of this order in Europe 

 in eocene deposits, and by the occurrence of an ostrich among the fossils of 

 the Siwalik Hills. 



While considering that no other form of animal inhabiting New Zealand 

 requires a land connection with distant countries to account for its presence, 

 Mr. Wallace concludes, in accordance with principles well estabhshed in an 

 earlier part of his work, that the existence is demonstrated of an extensive 

 tract of land in the vicinity of Australia, Polynesia, and the Antarctic 

 Continent, without having been actually connected with any of these 

 countries, since the period when mammalia had peopled all the great 

 continents. 



Last year the issue of Mr. Wallace's most interesting work on "Island 

 Life," added another contribution to our knowledge of the question under 

 discussion, and the three chapters devoted to New Zealand put the problems 

 very clearly before us. A very important factor, and one which had not 

 hitherto been considered, is now introduced — viz., the relative depths of the 

 seas surrounding Australia and New Zealand. It is shown, by the aid of a 

 map, that if the whole of the circumjacent ocean, which is at present less 

 than 1,000 fathoms in depth, was to be elevated above sea-level, a very 



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