36 THE GEOGRAPHY OF MAMMALS 



family now confined to America, and apparently dis- 

 tributed over the whole northern hemisphere during 

 Tertiary times, but not found in Australia — a certain 

 number of them show an Australian stamp. Some of 

 them have even been relegated by Ameghino (1), to 

 whose researches our knowledge of the Santa Cruzian 

 fauna is mainly due, to the existing Australian family 

 Dasyuridie. 



If, on further investigation, these references shall be 

 found to be correct, the inference would seem to be that in 

 very remote times — probably in the early Tertiary or the 

 late Secondary Period — there has been some sort of land- 

 connection between South America and Australia. In 

 such case there would be no necessity to suppose that 

 Australia was ever directly connected with the rest of the 

 Old World at all, none of the peculiar forms of Australian 

 Marsupials having yet been detected in any other part of 

 the globe. 



Besides the common possession of Marsupials, many 

 other resemblances between the faunas of Australia and 

 South America have been pointed out to occur among 

 the Birds and Amphibians, and especially among the Fishes. 

 Two families of freshwater fishes {Galaxiidse and Haplochi- 

 tonidse) are found exclusively in these two Regions, and 

 are not known to occur elsewhere. 



Apart from speculation, however, there is no question 

 that Australia has been isolated from all the other 

 continents since the end of the Secondary, or at least 

 since the beginning of the Tertiary Period of geological 

 time. 



