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SMITHSONIAN MISCELLANEOUS COLLECTIONS 
VOLUME 134, NUMBER 3 
Charles BD. and Mary Waux Walcott 
Research Fund 
BOOP DEVELOPMENT OP THE 
PENNSYLVANIAN TEREBRATULID 
CRYPTACANTHIA 
(WitH 2 Piates) 
By 
G. ARTHUR COOPER 
Head Curator, Department of Geology 
United States National Museum 
Smithsonian Institution 
(PusiicaTion 4267) 
CITY OF WASHINGTON 
PUBLISHED BY THE SMITHSONIAN INSTITUTION 
JANUARY 31, 1957 
