268 PROFESSOR OWEN ON THE GENUS DINORNIS. 



and reptile-like condition of the respiratory apparatus, we are thereby further jus- 

 tified in admitting the evidence of the co-existence of similar apterous and low orga- 

 nized birds with the cold-blooded and slower-breathing Ovipara, which swarmed in 

 such plenitude of development and diversity of forms during what has been termed 

 the 'Age of Reptiles.' 



The remarkable geographical distribution of the birds of the Struthious order, which 

 have no power of transporting themselves to distant isles or continents, either through 

 the air or the ocean', irresistibly leads us to speculate on the cause of that distribution, 

 and its connexion with the former extent and importance of the wingless terrestrial 

 birds. Hereupon it may first be remarked that those species, now in existence, which 

 have the least restricted powers of locomotion, enjoy the most extensive range for their 

 exercise. 



The Ostrich is spread over nearly the whole of Africa, from the Cape to the deserts 

 of Arabia ; beyond which the species is unknown. The Rhea ranges over a great part 

 of the southern extremity of the Western hemisphere. To the Emeu has been assigned 

 the vast mainland of Australia. The heavier Cassowary is limited to a few of the islands 

 of the Indian Archipelago. The Dodo appears to have been confined to the Mauritius 

 and the small adjoining Isle of Rodriguez. The Apteryx still lingers in New Zealand, 

 where alone any specimens of that most anomalous species of the Struthious order have 

 been discovered. 



New Zealand was, also, at one period, the seat of a seventh genus of Struthionida ; 

 and it is worthy of remark that the Fauna of no other island, nor of any of the great 

 continents, has yet furnished an analogous example of two distinct genera of that group 

 of birds. Moreover the most gigantic as well as the most diminutive species of the 

 wingless group — always to Ornithologists most remarkable for the great size of its spe- 

 cies — formerly occupied their place amid the fern-thickets and turbaries of New Zealand. 

 And, again, the number of the species of Struthionida in this island equalled that in all 

 the rest of the world, as registered in the catalogues of Ornithology. 



Now, since all the larger existing Struthious birds derive their subsistence from the 

 vegetable kingdom, we may hope to receive from the botanist an elucidation of the 

 circumstances which favoured the existence of so many large birds of this order in the 

 remote and restricted locality where alone their remains have hitherto been found. It 

 seems, at least, most natural to suppose that some peculiarity in the vegetation of New 

 Zealand adapted that island to be the seat of apterous tridactyle birds, so unusually 

 numerous in species and some of them of so stupendous a size. 



The predominance of plants of the Fern-tribe, and the nutritious quahties of the roots 

 of the species most common in New Zealand, are the characteristics of its Flora which 



' The Rhea and Emeu have heen seen to take water for the purpose of crossing rivers and narrow channels 

 of the sea ; but almost the entire body sinks below the surface, and their progress is slow, as might be anticipated 

 from the absence of the swimming-webs in their feet. See Darwin, ' Voyage of the Beagle,' vol. iii. p. 105. 



