PILSBRY: NON-MARINE MOLLUSCA OF PATAGONIA. 



621 



exactly contrary to the actual facts of molluscan distribution. All African or 

 Archhelenic forms which exist in the Antilles are unequivocally of the South 

 American type, and certainly indicate that there was no later migration 

 or communication from Africa in the north. There seems little evidence 



FIG. 28. 



FIG. 29. 



a& 



Distribution o f Ortlialiciiue. Oxystyla 

 spreads throughout the black area except in 

 the Antilles. Number of genera in each 

 district indicated by numerals. 



Distribution of Plekocheilus, a genus of 

 Guiana-Colombian origin, spreading south- 

 ward in the late Tertiary. 



for the Upper Cretaceous "Mesozonia," mapped by Dr. Ortmann, and 

 there are very strong reasons for holding that no such land existed. 



Dr. von Ihering 1 holds that the subsidence of the Brazil-Ethiopian 

 continent began in the north during the Cretaceous. 



1 Archhelenis und Archinotis, p. 337. 



