182 TEETIARY ROCKS OF AUSTRALASIA, 



As regards the relationship of the various Australasian 

 leaf-beds to each other, and their exact position within 

 the period, there is much that is uncertain and obscure. 

 It is true that the learned authority, for whom the author 

 entertains the highest respect, has referred the Travertin 

 beds at Risdon and other leaf-beds of the Derwent near 

 Hobart to Miocene age, while beds containing a very 

 similar flora in New South Wales (Dalton and Vegetable 

 Creek) have been referred to Eocene, and even Lower 

 Eocene age ; but as the author has recently discovered a 

 characteristic species of the Derwent (Sapotacites oligo- 

 neuris, Ett.) intercalated with other plant impressions in 

 marine beds at Table Cape, deemed to be of Eocene age, 

 it proves that it is hazardous to attempt to define their 

 position in accordance with the nomenclature of Europe, 

 and especially with the particular association of genera 

 found there within definite local subdivisions. 



The reference to the wider grouping {Palceogene), as 

 adopted by the author, appears to be the safer course at 

 present, when vv'e take into consideration the great dif- 

 ference in longitude and latitude of the deposits referred 

 to, and the possible original differences of elevation. 



Fauna. 



The Austrahan Tertiary Eauna, as a whole, also pre- 

 sents a clearly modern aspect. The foraminifers, brachio- 

 pods, gasteropods, pteropods, and pelecypods nearly all 

 belong to genera still existing in Australian seas. Of the 

 Tertiary molluscs of Australia and Tasmania, however, 

 there is, according to latest accounts, not more than 2 

 per cent, of the species identical with existing forms. 

 Fishes of the shark family are alone known, and these are 

 represented by four genera (^Carcharodon, Lamna, Otodus, 

 Oxyrhina). all of which have living congeners. The car- 

 nivora are represented by a member of the seal family 

 {Ar otocephalus Williamsi, M'Coy) ; and Cetaceans, by the 

 characteristic genera Squalodon and Zeugolodon. Profes- 

 sor M'Coy has also figured three species of Cetotolites 

 from the Tertiary beds near Geelong, which are declared 

 to be the ear-bones of different species of whales. 



Perhaps the most interesting group of mammals, so far 

 as Australia is concerned, is the ancestral types of the 

 existing marsupials. As yet the more remarkable forms 



