Fauna and Flora of New Zealand. 445 
identical with those of Australia, prove that this extension 
was much less than the other two, and perhaps 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 forests, and difficult to explore geologically, and the 
fossils, although largely collected, have as yet been but 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 commonly discontinuous, require the aid of 
paleontology for their elucidation more than in most coun- 
tries. Nevertheless, thanks to the energy and skill with 
which the Geological Survey department has during the last 
twenty-two years attacked the problem, I think [ am safe in 
saying that the main structure of thé country is tolerably well 
known, especially in those points which alone concern us 
here, and which [ will briefly mention. 
The main range forming the New-Zealand Alps in the 
South Island, and the mountains stretching from Wellington 
towards the East Cape in the North Island, is composed of 
highly-inclined sedimentary rocks belonging to four, or per- 
haps five, distinct systems. The first is probably Archean or 
Cambrian. According to Dr. Hector the second is Ordovi- 
cian, the third Silurian and Lower Devonian, the fourth Upper 
Devonian and Lower Carboniferous, while the fifth ranges 
from Permian to Jurassic. ‘This last system contains fossils 
related to those from the Gondwana system of India and the 
newer Carbonaceous system of Hastern Australia. According 
to Mr. 8. H. Cox, it is about 21,000 feet in thickness, and is 
entirely a littoral formation, plant-remains being found all 
through it; thus implying a subsidence of 3500 fathoms in 
early Mesozoic times. ‘The axis of the geanticlinal, however, 
is not in the centre of the range, but lies along its western 
base, the whole western portion of the elevated mass having 
been removed by denudation, except in the west part of 
Nelson and the north part of Auckland. Of the rest, all that 
remains is the submarine plateau which stretches out towards 
Australia. 
The next system of rocks is of Cretaceous, probably Upper 
Cretaceous, age*. Along the eastern base of the main range 
it lies quite unconformably on the Jurassic and older rocks, 
and, according to Dr. Hector and Dr. von Haast, it is also 
* Dr. Hector considers the oldest beds to be the equivalent of the Lower 
Greensand of England. 
