May-June 1921, " Been | Lee ae 
EDITED BY 
THOMAS Oe ‘CHAMBERLIN AND ROLLIN Ds SALISBURY _ 
With the Active Collaboration of . " 
STUART WELLER : Ape JOHANN SEN 
‘ Invertebrate Paleontology < Peoes 
EDSON S. BASTIN ROLLIN T. CHAMBERLIN 
_ Economic Geology ~ veer Dynamic Geology 
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