PILSBRY: non-marine MOLLUSCA of PATAGONIA. 



617 



massifs. This connection of the Brazilian and Guiana-Colombian areas 

 must have persisted long after the Archhclenic period, for distinctively 



Fig. 21. 



Distribution of the land-snail family StreptaxidcB. 



Fig. 22. 



C/ i^Vt, 



Distribution of fresh-water snails of the i3.m\\y A)npu/lanida;, havingthe operculum wholly corneous. 



American genera had been differentiated. It wa's interrupted prior to the 

 union with the Antillean-Mexican continent, since the genera of that area 



