HASEMAN, GEOGRAPHICAL DISTRIB UTION IN SOUTH AMERICA 103 



along its northern portion, the fan-shaped trend lines west of Pernam- 

 buco which fade away toward the coast and are roughly comparable to a 

 somewhat analogous condition in the region of La Paz, Bolivia, its recent 

 slight elevation, its lack of numerous islands separated by comparatively 

 shallow sea and its abruptness being primarily due to erosion of Paleozoic 

 and post-Paleozoic land deposits and not to post-Paleozoic faulting, indi- 

 cate that South America was never connected with the eastern hemi- 

 sphere. This view is further strengthened by the absence of deep-sea 

 ooze, etc., from the continental shelves and the abundance of sharks' 

 teeth in the great ocean depths which indicate a vast antiquity for the 

 abysmal depths. 



We have noted many facts concerning the South American topography, 

 the most interesting of which were the cases of stream piracy existing 

 between Eio Orinoco and Eio Negro, and Eio Sao Francisco and Eio 

 Tocantins. The Paraguay Eiver is not connected with the Amazon. 

 These facts, taken in connection with waterfalls, altitude, swamp produc- 

 tion, erosion and the composition of environmental complexes, have led to 

 some interesting results concerning the distribution of the South Amer- 

 ican fishes. 



Using the cichlid fishes only as the best known family of South Amer- 

 ican animals, it has been shown that isolation or barriers and interming- 

 ling or river connections utterly fail to explain their distribution. It was 

 found that the present distribution of the fishes is correctly explained by 

 the organic complex of the more generalized highland genera (which are 

 small in size and naturally widely distributed because the Piano Alto was 

 formerly a continuous unit) and by the action of the environmental com- 

 plexes on this stock. In other words, when the common ancestral forms 

 arrived in similar environments, i. e., similar environments were eroded 

 in the Piano Alto, they evolved along similar and identical lines and in 

 different environments along different lines. 



When we attempted to determine the point of origin and lines of dis- 

 persal of families and orders, it was found to be absolutely necessary to 

 invoke the aid of fossils. In doing this, it was found necessary to use 

 more than single physiological characters and draw a sharp distinction 

 between paleotelic and cenotelic characters. When this was done, the 

 fishes evidently point to a northern origin and not to an African-South 

 American Gondwana origin. 



When similar methods were applied to the Permian reptiles, Gondwana 

 flora, mammals and other alleged evidence in favor of connections be- 

 tween South America and the eastern hemisphere, the evidence was not 

 found convincing for a single case. Thus the Permian reptiles, if crit- 



