6oo 



T. C. CHAM BERLIN 



fauna, and if this, for like geographic reasons, was permitted to 

 reach Europe in stage B, and America in stage C, a different 

 set of errors of interpretation would be likely to arise from the 

 simple criterion of community of species, for the commingled 

 faunas would appear in America and Asia only in stage C, while 

 they would appear in Europe as early as stage B. So too, in 



Stage C 



Stage B 



Stage A 



America 



Europe 



Asia 



America and Asia, in stages A and B, only the respective pro- 

 vincial faunas would be found. The situation is illustrated in 

 the accompanying diagram. But if the fact of the provincial 

 origins of the two faunas and their subsequent migration can be 

 established, a much more accurate correlation will be possible. 

 The deposits of stage A in Asia and America will be correctly 



