C HAP. XXI.] 
NEW ZEALAND. 
449 
— It has been well observed by Captain Hutton, in his inter- 
esting paper already referred to, that the occurrence of such a 
number of species of Struthious birds living together in so 
small a country as New Zealand is altogether unparalleled else- 
where on the globe. This is even more remarkable when we 
consider that the species are not equally divided between the 
two islands, for remains of no less than ten out of the eleven 
known species of Dinornis have been found in a single swamp 
in the South Island, where also three of the species of Apteryx 
occur. The New Zealand Struthiones, in fact, very nearly equal 
in number those of all the rest of the world, and nowhere else 
do more than three species occur in any one continent or island, 
while no more than two ever occur in the same district. Thus, 
there'appear to be two closely allied species of ostriches inhabiting 
Africa and South-western Asia respectively. South America 
has three species of Rhea, each in a separate district. Australia 
has an eastern and a western variety of emu, and a cassowary 
in the north ; while eight other cassowaries are known from the 
islands north of Australia — one from Ceram, two from the Aru 
Islands, one from Jobie, one from New Britain, and three from 
New Guinea — but of these last one is confined to the northern 
and another to the southern part of the island. 
This law, of the distribution of allied species in separate areas 
— which is found to apply more or less accurately to all classes 
of animals — is so entirely opposed to the crowding together of 
no less than fifteen species of wingless birds in the small area of 
New Zealand, that the idea is at once suggested of great geogra- 
phical changes. Captain Hutton points out that if the islands 
from Ceram to New Britain were to become joined together, we 
should have a large number of species of cassowary (perhaps 
several more than are yet discovered) in one land area. If now 
this land were gradually to be submerged, leaving a central 
elevated region, the different species would become crowded, 
together in this portion just as the moas and kiwis were in 
New Zealand. But we also require, at some remote epoch, a more 
or less complete union of the islands now inhabited by the 
separate species of cassowaries, in order that the common 
ancestral form which afterwards became modified into these 
G G 
