NATK )NAL ACADEMY OF SCIENCES. 



Volume X. 



FIFTH MEMOIR. 



THE AFFINITIES OF THE PELAGIC TUNICATES. 



No. 1. ON A NEW PYROSOMA. 

 (Dijil' urosoma tllijifica.) 



BY 



WILLIAM KEITH BROOKS, 



HENRY WALTERS PROFESSOR OF ZOOLOGY IN THE JOHNS HOPKINS UNIVERSITY. 



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