HASEMAN, GEOGRAPHICAL DISTRIB UTION IN SO VTH AMERICA 93 



some distance, such as might have intervened between South Africa and 

 the nearest Antarctic islands. If any of them were spore-bearing, then 

 wind distribution would be an important factor, as it is in the case of 

 puff-balls and ferns. It is then important to settle definitely whether any 

 or all of the early Gangamopteris flora were seed-bearing or sporogenous. 



The last possible mode of distribution is by the way of the sea. David 

 White has informed me that some of the seeds may have been able to 

 survive marine drift for some time. He thinks that the migration was 

 by the Antarctic, and if by the way of the sea, it would have been with a 

 minimum interruption by water. He suggests that it would perhaps be 

 better to say that migration was probably by several lands and not by a 

 continuous Gondwana Land. As the facts indicate, however, this flora 

 was a highland flora, and hence few or none of the species could have 

 been distributed in this way unless they lived on low coastal sandy high- 

 lands or campos such as exist in parts of Eio Grande do Sul, Brazil. 



In conclusion, we may safely say that we do not definitely know where 

 the Gangamopteris flora originated, how and which way it dispersed, 

 why it appeared and disappeared in Brazil during the formation of the 

 Piano Alto and why so many species and genera remained almost iden- 

 tical in such remote regions as India and Brazil during most of the 

 Permian epoch. 



The distribution of the Permian reptiles, the deep intervening sea, the 

 trend of the Archean mountains, the mode of the formation of the Per- 

 mian deposits, the location of marine deposits and the evidence in favor 

 of the persistence of the great ocean depths and the continental shelves 

 offer conclusive evidence that no continuous Gondwana Land has existed 

 between South America and the eastern hemisphere, at least since Car- 

 boniferous time. Previous to this, it may have existed, but many data 

 are needed to prove that it did. 



In view of the fact that the Gangamopteris flora once formed did not 

 appear to vary, we have only to explain how it got, one time, into such 

 remote regions as India, Africa and Brazil, because a continuous ex- 

 change of the flora would have been unnecessary. Therefore an acci- 

 dental marine drift of the seeds and the wind, if any were sporogenous, 

 by way of the Antarctic islands are possible means of distribution, but I 

 believe that the distribution of the ancestral stock was along the Asiatic- 

 American "backbone" of the earth and a subsequent similar evolution in 

 similar environments or else orthogenesis of this stock agrees better with 

 the known data relating to geographical distribution. 



The widely accepted view of a continuous Gondwana Land has been 

 derived from the static viewpoint of living and extinct animal and plant 



