FAUNA AND FLORA OF NEW ZEALAND. 17 
cation ; for Professor Huxley has pointed out that fresh-water 
crayfishes are very ill-adapted for crossing even a narrow arm of 
the sea. Mr. Wallace thinks that this connection with Fiji “is 
hardly probable, or we should find more community between the 
productions ” of the two countries; but when we remember the 
difference of climate we cannot expect a greater community 
than actually exists. The marine crustacea agree with the ma- 
rine fishes and shells, in having well-marked Australian and 
Antarctic elements, but perhaps it is not yet possible to distin- 
suish South American from Antarctic forms. It will not be 
necessary to pass in review the lower classes of animals. But 
little is as yet known of them, and at present they throw no new 
light on the origin of our fauna. 
I will now recapitulate the results we have arrived at about 
the New Zealand flora and fauna. The South American ele- 
ment in the fauna and flora, as shewn by the plants, frog, land 
mollusca, and insects, proves that New Zealand was clearly con- 
nected with the South Pacific continent which probably existed 
in jurassic and lower cretaceous times, while the distribution of 
the fresh-water crayfishes proves that Fiji and New Zealand 
have had a continuous land communication. The distribution 
of the marine mollusca shews that New Zealand has been sepa- 
rated from all northern lands ever since the cretaceous period, 
and this explains the fragmentary nature of the avi-fauna. At 
the same time the fact that many birds, land-shells, and plants, 
shewing no South American relations, have passed to New Zea- 
land from the north-west, proves that these islands, although not 
actually connected, must have extended much farther north and 
approached much more nearly to Queensland and New Guinea 
at some period in the tertiary era than they do now, and that 
that period was an early one is shewn by the amount of change 
that has since taken place both in plants and animals. The 
flora of the Kermadec Islands, and the remarkable phenomenon 
of our migratory cuckoos, give evidence of a third north-easterly 
extension of New Zealand at a much later date ; but the absence 
of many common types of Australian birds, and the small num- 
ber of northern plants and animals specifically identical with 
those of Australia, proves that this extension was much less 
than the other two, and perhaps it did not last long. It is now 
necessary to examine the geology of New Zealand, and see how 
it bears on the subject. 
New Zealand is a mountainous country, partly covered with 
forest, and difficult to explore geologically, and the fossils, al- 
though largely collected, have as yet been little studied. It is 
not, therefore, surprising that many points in its geology remain 
uncertain, especially as to the ages to be assigned to the several 
rock systems of which it is composed ; and which, being com- 
monly discontinuous, require the aid of paleontology for their 
elucidation more than in most countries. Nevertheless, thanks 
to the energy and skill with which the Geological Survey de- 
partment has during the last twenty-two years attacked the 
