XI PAX^ONTOLOGY AND EVOLUTION 387 



dry land existed in North Ameiica, Europe, Asia, 

 and Africa, as it does now. Into this great new 

 continental area the Mammals, Birds, and Rejjtiles 

 developed during the Palaeozoic epoch spread, and 

 formed the great Triassic Arctoga^al province. 

 But, at the end of the Triassic period, the move- 

 ment of depression recommenced in our area, 

 though it was doubtless balanced by elevation 

 elsewhere ; modification and development, checked 

 in the one province, went on in that " elsewhere " ; 

 and the chief forms of Mammals, Birds and Rep- 

 tiles, as we know them, were evolved and peopled 

 the Mesozoic continent. I conceive Australia to 

 have become separated from the continent as early 

 as the end of the Triassic epoch, or not much 

 later. The Mesozoic continent must, I conceive, 

 have lain to the east, about the shores of the 

 North Pacific and Indian Oceans ; and I am 

 inclined to believe that it continued along the 

 eastern side of the Pacific area to what is now the 

 province of Austro-Columbia, the characteristic 

 fauna of which is probably a remnant of the popu- 

 lation of the latter part of this period. 



Towards the latter part of the Mesozoic 

 period the movement of upheaval around the 

 shores of the Atlantic once more recommenced, 

 and was very probably accompanied by a de- 

 pression around those of the Pacific. The Verte- 

 brate fauna elaborated in the Mesozoic continent 

 moved westward and took possession of the new 



