352 Glacial Period in the [July? 
in America, nor even so much as in Europe amongst the 
great mammals. Numerous bones of the moas are found in 
the stratified deposits of the plains, but the same species 
reappear in the post-glacial surface-beds. Their complete 
destruction did not take place at the same time as the 
megatherium and its associates in America, or the mammoth 
and the woolly rhinoceros in Europe, but must rather be 
correlated with that of the Irish elk and the American 
mastodon. The preservation of the large birds through the 
great vicissitudes of the Glacial period may have been owing 
to the following causes : — Long before the ice from the 
Antarctic reached the coasts of New Zealand, a great stretch 
of land to the north would be laid dry by the lowering of 
the sea-level, so that there was possibly more space suitable 
for their occupation during the greatest extension of the ice 
than now. The same lowering of the sea-level took place 
all over the world, and in South America a similar extension 
of land surface must have ensued ; but there the new land, 
to the north of the districts glaciated or submerged beneath 
the waters of the great glacial lake, would be occupied by 
northern animals who would resist the immigration of those 
fleeing the catastrophes of the south. In New Zealand, 
also, there was not the same competition with smaller ani- 
mals, which appears to have led to the extirpation of many 
of the bulky species of the continents during the changing 
conditions of the Glacial period. Had, for instance, New 
Zealand at that time become connected with Australia, the 
great extension of area thus obtained, instead of tending 
to the preservation of the moas, would have probably led 
to their extermination by bringing them into competition 
with the marsupials of the continent. But a channel, 
2600 fathoms deep, separates the two countries ; and that 
there was then no land connection between them is evi- 
denced by the absence of the gum-trees and acacias of 
Australia from the flora of New Zealand, and of the marsu- 
pials, the cockatoos, the grass parroquets, and the pigeons 
of the former from its fauna. 
Although the large apterous birds of New Zealand were 
not exterminated during the great glaciation of the country, 
there are other signs of the impoverishment of its fauna. 
About 200 species of beetles had been described in 1872, 
and these belonged to no less than no genera, giving an 
average of less than two species to each genus. Many of 
the species live also in Australia, or have nearly allied forms 
there. The great paucity of inseCts, the isolation of the 
species, and their affinity with those of Tasmania and 
