128

106

and reptile-like condition of the respiratory apparatus, we are therefore 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 1, 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 Struthionidae ;
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 bird. 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 Struthionidae 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 and 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 usually
numerous in species and some of them of so stupendous a size.

The predominance of plants of the Fern-tribe, and the nutritious qualities of the roots
of the species most common in New Zealand, are the characteristics of its Flora which

1 The Rhea and Emeu have been 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.