26 THE 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, t 
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, 1905-11. 
} History of Mammals, p. 127, 1896. 
{ 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. 
