4GG ZOOLOGICAL GEOGRAPHY. [part hi. 



disappear during an entire rotation of the earth. During such 

 a period, tropical forms of marine animals would have been able 

 to spread north and south, into what are now cool latitudes ; and 

 identical genera, and even species, might then have ranged along 

 the southern shores of the old Palsearctic continent, from Britain 

 to the Bay of Bengal, and southward along the Malayan coasts 

 to Australia. 



Numerous Miocene plant-beds have also been found in Vic- 

 toria, containing abundance of Dicotyledonous leaves, which are 

 said generally to resemble those of the Asiatic flora, and of the 

 Miocene plant-beds of the Khine. It is to be hoped these beds 

 will be more closely examined for remains of insects, land-shells, 

 and vertebrates, and that the plants will be carefully preserved and 

 critically studied ; for here probably lies hidden the key, that 

 will solve much of the mystery that attaches to the past history 

 of the Australian fauna. 



