20 Pratt, Bipolar Theory. 



thanks are also due to Dr. Gamble and Dr. Ashvvorth 

 for information on Arenicola, and to the latter also 

 for notes on the distribution of Scalibregma, to Dr. 

 Appellof, of Bergen, for the loan of specimens of Goniada 

 norvegica, and to Dr. Willey, who drew my attention to 

 certain " bipolar " Polych^eta which I had overlooked. 



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