A Trip to Mar del Plata 205 



there may have been a connection with Australia. 

 The fact that fossil marsupial animals are very numer- 

 ous in these early strata, and further the fact that there 

 are still comparatively numerous marsupial animals 

 living in South America, supports the view that South 

 America may in the distant past have been in some way 

 connected with the Australian regions, which are, as 

 everybody knows, the present metropolis of the mar- 

 supials. There may also have been a time, when, for 

 a longer or shorter period, the southern extremity of 

 Africa was also linked to that old Antarctic continent. 

 The fact that certain families of shells, insects, fishes, 

 birds, and mammals occur in regions now separated 

 from each other by wide seas, is regarded by students 

 as showing the probability that these regions were once 

 more closely connected with each other than they now 

 are. A multitude of facts in the geographical distribu- 

 tion of living things, which it would require a volume 

 to recite, tends to confirm the opinion, now almost 

 universally accepted by naturalists, that the land- 

 masses about the South Pole once had a much greater 

 northward extension than is the case to-day, and that 

 Australia and the southern extremities of South Amer- 

 ica and of Africa may have been connected at times with 

 Antarctica, and thus with each other. At the times 

 when these parts of the earth were being populated by 

 living things, these regions were completely isolated 

 from the lands in the northern hemisphere. The 

 great land-mass forming Europe and Asia (the Eurasian 

 continent) was at different times connected with North 

 America. There is every reason to believe that North 

 America and eastern Asia were once united with each 

 other by a land-bridge, which was located in the region 

 of Bering Sea, and that animals freely migrated from 



