110 Scientific Proceedings, Royal Dublin Society. 
through the time of the deposit of the lake sediment, or the 
second stage of the glacial period, called that of the “sands and 
gravels;” and that the rigours of the climate of the second 
glacial period or Upper Boulder clay, by preventing vegetation, and 
consequently destroying its supply of food, effected its total ex- 
tinction, at least in this island; and being insular (as likely our 
connexion with England had ceased, so that it could not migrate), 
it perished. We can thus account for the absence of vivianite in 
the top clay—the animal having become extict, the supply of 
phosphoric acid from the bones of the drowned animals had 
ceased. 
And now a few words about the deposit of these clays. The 
smallness of the catchment basin, and its elevation, caused the 
operation to be carried on in a state of perfect quiet—hence, all 
is well defined. There was no extensive mountain slope down 
which a glacier could move—hence, none of those disturbances 
of the beds which so often puzzle geologists—hence, the appear- 
ances are more reliable. The snows of the long winters covered 
the low hills which surround the valley; the severe frosts split 
and disintegrated the granite; in the short summers the thaws 
brought down the debris into the larger lake, where we find it 
covering up the true lake sediment; the waters became turbid 
and flowed into the smaller lake, and there deposited, forming the 
beds we have been considering. We owe the good state of 
preservation in which the remains are obtained to the bed of 
arctic clay which covered up the contents of the lake. 
While contemplating the effects which the Arctic climate pro- 
duced in this locality, we must remember that similar influences 
were at work over the whole world. Hence, the severity of that 
climate which (if our theory be correct) destroyed the Megaceros 
may have been the means of the extinction of the Siberian mam- 
moth, the mastodon of North America, the megatherium and mylo- 
don of South America, the great kangaroos of Australia, the moa 
of New Zealand, the mammoth, rhinoceros, hippopotamus, the 
cave bear, lion and hyenas of England. Dr. Geikie said to me 
some short time ago, “there cannot be a doubt of it that the Ice 
Age killed off the great Mammalia.” In short, these former ten- 
ants of our planet seem to have been evicted by the frost; and 
