26 THK DESEADO FORMATION OF PATAGONIA 



late as Tertiary times; but to my mind this involves a 

 connection which is most too difficult to postulate. There 

 is no evidence that they came to South America in com- 

 pany with other faunas, for they have not been found 

 associated with any other fauna outside of Southern Pata- 

 gonia. The explanation of the affinities of the Patagonian 

 marsupials with the Australian marsupials is a problem 

 which is not yet in position to be settled. 



The birds probably came from Africa with the invasion 

 of the ancestors of the Notungulates. 



The idea of an invasion from Africa in Upper Cretaceous 

 times, and possibly another at a later time is correlated 

 with the other evidence of a land bridge between these two 

 continents, as deduced by students of other groups. 



Eigenmann, working on the freshwater fishes,* 

 Lydekker, studying the hystricomorphs,f 

 Von Ihering, studying the freshwater mussels, J 

 Ortmann, studying the freshwater crabs, 



not to mention several others studying mullocks, insects, 

 plants, etc., have all postulated a land connection from 

 Brazil to northern Africa during Cretaceous time to ex- 

 plain the distribution of their various groups. The diver- 

 gence is in the time when this land bridge sank, some be- 

 lieving it to have lasted into Tertiary times, most feeling 

 that it sank in Upper Cretaceous times. Another body 

 of evidence is presented to show that a land bridge con- 

 nected the West Indies with the Mediterranean regions.!! 

 There was presumably but one such transatlantic connec- 

 tion. Its position further to the south would seem to me to 

 explain the distributional facts found in the West Indies, 

 but the striking resemblances between the faunas of Africa 



* Princeton Expeditions to Patagonia, vol. 3, p. 310, 1905- n. 



t History of Mammals, p. 127, 1896. 



J Archhelenis and Archinotis, p. 125-145, 1907. 



Proc. Amer. Philos. Soc. Philadelphia, vol. 41, p. 350, 1902. 



|| See Scharff, Distribution and Origin of Life in America, Ch. 11, 1912. 



