iS77*] 
Southern Hemisphere. 
351 
would be melting itself instead of freezing the water it came 
in contact with. There is no more reason for the lakes it 
caused being frozen than that the Manjalen Sea — which is 
formed in a similar way — should be so. 
The advance of the circumpolar ice-sheets in the form of 
low ridges, rising very gradually from their outer edges and 
culminating at a height of perhaps not more than 8000 or 
10,000 feet above the present level of the sea, and then de- 
creasing in height towards the Poles again, in consequence 
of the moisture being precipitated on the outer slopes, is, I 
think, more in accordance with our experience than the 
usual form of the theory of ice-caps, which would make 
them highest at the Poles. The latter supposition, it has 
been shown, is opposed to the fadts that the ice flowed 
northward from the northern end of Scandinavia ; that the 
high peaks of the Lofoden Isles are not glaciated ; and 
especially that at the present time the northern end of 
Greenland is much more free from ice than the southern 
extremity. Whilst every inlet of South Greenland is occu- 
pied by ice flowing from the interior, and breaking off into 
great bergs when it arrives at sufficiently deep water, in the 
extreme north the glaciers do not reach the level of the sea. 
And in the Glacial period, instead of there being more ice 
than now within the Arctic and Antardtic circles, there was 
probably much less. Within the ridge of ice that then, I 
think, irregularly encircled the southern hemisphere, and, in 
the northern, bridged across the northern ends of the 
Pacific and Atlantic Oceans, both plants and animals that 
could hybernate through the severe and long winters might 
have existed in greater abundance than now. Even now, 
in the Antardtic, behind the ridge of ice that surrounds the 
South Polar continent, it is possible that there may be large 
areas of land free from ice in summer, and supporting a flora 
and fauna, which, if they could be studied, might throw 
much light on the distribution of animal and vegetable life 
in the South Temperate zone. And were that barrier of ice 
once passed a journey to the South Pole might be found to 
be less impracticable than one to the northern extremity of 
the globe. 
Whilst the physical phenomena of the Glacial period in 
New Zealand and South America are so similar, there are 
differences in its effedt on the pre-glacial fauna that must be 
noticed. Although there was great destruction of life 
amongst the individuals of the great apterous birds of New 
Zealand, there was not the same extirpation of species as 
