1830. ANNIVERSARY MEIIOIRS OF THE BOSTON SOCIETY OF NATUKAL HISTORY. 18S0. 



A STRUCTURAL FEATURE, 

 HITHERTO UNKNOWN AMONG ECHINODERMATA, 



FOUND IN 



DEEP-SEA OPHIURANS. 



By THEODORE LYMAN. 



[Printed by permission of Hon. Carlile P. Patterson, Supt. U. S. Coast-Survey ; and of the Lords Commissioners of tlie Treasury, England.] 



BOSTON: 



PUBLISHED BY THE SOCIETY. 

 1880. 



