; 86 Transactions. — Zoology. 



genera and numerous species, varying considerably in stature, 



all mixed up indiscriminately together, showing that these 



. birds Lad inhabited the plains of Canterbury at one and the 



• same time. I have endeavoured to furnish an explanation of 

 this in my introduction to " The Birds of New Zealand," 

 pages xxxiv., xxxv. Adopting a theory first put forward 

 by Professor Hutton — to whom I acknowledge my indebted- 

 ness — I have attempted to show how this could have been 

 brought about by natural causes. By going much further 

 back in time — and that is the charm of the evolution theory, 

 that it imposes practically no limits as to time and space — I 



• have supposed that in very ancient times two or more species of 



• brevipennate birds, themselves the descendants of volant birds 

 of a still earlier epoch, roamed over a great southern conti- 



' nent, which, by some convulsion of nature, was afterwards 

 submerged, leaving its higher levels and mountain-tops ex- 

 posed in the form of numerous scattered islands, on which the 

 survivors of the wingless race of birds would naturally remain; 

 that this state of things continued long enough — how long it 

 is impossible even to conjecture — for the inhabitants of each 

 island to develope new characters suited to their special en- 

 vironment in each case, thus bringing into existence in the 

 end the various species of Dinornis and its allies as we now 

 know them ; that a widespread upheaval or elevation of the 

 land followed, reuniting most of the islands, and resulting in 

 the areas now known to us as the Islands of New Zealand, 

 when, of course, the Struthious birds which had been deve- 

 loped in the smaller insular areas would be able, in process of 

 time, to commingle on common ground. " In process of time," 

 I say, because it would naturally take a considerable time for 

 the newly-elevated areas to become covered with vegetation, 

 although, on the other hand, it is quite possible that this 

 elevation may have been gradual in its operation everywhere. 

 I suggested that when, by the gradual subsidence of their 

 domain beneath the waters of the great Pacific, they were 

 driven as it were into a corner and overcrowded, the struggle 



■ for existence became a severe one, and the extinction of the 

 race then commenced ; that the more unwieldy giants, thus 

 cabined and confined, were the first to succumb; and that the 



• smaller species, perhaps in course of time differentiated from 

 their ancestors by the altered physical conditions of their 

 environment, continued to live on till their final extirpation by 



I man within recent historic times. Professor Hutton supposes 

 two successive submergences and elevations of the land at 

 long intervals, but in this I am unable to follow him. With- 

 [ out that, the theory is sufficient, I think, to account for the 

 - co-existence in comparatively recent times of the various 

 .genera and species. But, as the modifications in form and 



