140 TERTIARY ROCKS OF AUSTRALASIA, 



temperate forms from whatever Antarctic lands or islands 

 then existed. The marsupial fauna had not yet entered 

 this eastern land, which was, however, occupied in the 

 north by some ancestral struthious birds,, which had 

 reached it by way of New Guinea through some very 

 ancient continental extension, and of which the emu, the 

 cassowaries, the extinct Dromornis of Queensland, and 

 the moas and kiwis of New Zealand, are the modified 

 descendants." 



From this interesting sketch of the earlier condition of 

 Australasia much may be learned respecting the vast 

 extent of the terrestrial changes which have taken place 

 since the close of the Mesozoic period. It is also obvious 

 that the changes in the alternation of sea and land in the 

 northern hemisphere, and the character of the typical 

 organisms which occupied the areas determined by these 

 changes, must present strikmg differences as compared 

 with contemporaneous changes in the southern hemis- 

 phere ; and that, while on the broad lines of epochs or 

 systems there may be many points of agreement, it would 

 scarcely be wise to expect that the subdivisions of the 

 period should offer any approach to agreement either 

 with respect to their extent or number ; and, as regards 

 the terrestrial life of these subdivisions, we must also be 

 prepared to expect wide differences, although agreeing in 

 some of the broader distinctions which in a general way 

 mark the Mesozoic and Tertiary epochs. 



The nature and composition of the formations have 

 already been referred to. As regards the life of the 

 period, the most distinguishing features observed in con- 

 trast with the preceding one are the introduction of types 

 of life which characterise the existing period. We find 

 that the reign of the lycopods, cycads, and yew-like conifers 

 has given way to that of the beech, oak, elm, willow, 

 cinnamon, banksia, eucalyptus, and other angiosperms. 

 This transition, it is true, was not abrupt, for the dawn 

 of the new types had already made an appearance in 

 many countries towards the close of the Mesozoic period 

 (Cretaceous). The ammonites, belemnites, inocerami, 

 scaphites, and other characteristic types of the Mesozoic 

 rocks, disappear or sink into insignificance^ and their places 

 are taken by molluscs closely resembling existing forms, 

 and belonging in most cases to identical genera. Towards 



