U. S BioLoaiCAi SLRViiy 



Fourth Provisionai 



ZONE MAP OP NORTH AMERICA 



C. Hart Merruim, Vernon Bailey. E. W Nelson 

 10 - and E A Preble 



nedottedpariso/ the Austral Zoneseasto/ tilt Oreat Plaim indicate the extent of the h^ __ 

 nonsoftheeeZones.knoum respectively as the Alleghanian,CaroUnian,a7idAU3trariparianFaurias 

 mtZonesarehnoumastheTVansition, Upper Sfmoran. and Lower Sonoran. 



Theundottedpartt of thesan 



