BIOLOGICAL BULLETIN 



OF THE 



fiDarine Biological laboratory 



WOODS HOLE, MASS. 



VOL. L 



JUNE, 1926 



No. 



PAYNE, FERXAXDUS. 



BECKER, ELERY RONALD. 



HINRICHS, MARIE A. 



HINRICHS, MARIE A. 



MILLER, HARRY M., JR. 



HAMMETT. FREDERICK S. 



KEPNER, \\"M. A., 



AND LOOPER, J. B. 



CONTENTS 



Further Studies on tin- Life History of Cras 

 pedaciista ryderi, a Lresh-icater Hydro- 

 medusa n .............................. 



Endam/eha eilelli sp. noi\ from llie Striped 

 Ground Squirrel Cilellns iridecemlineatus, 

 mul tile Life-History of its Parasite, 

 endamceb<z sp. nov ............ 



Modification of Development on the Basis 

 of Differential Snsreptihilitv to Radiatio-i, 

 HI. 



The Effect of Ultraviolet Radiation on the 

 Fertilizing Poieer of Arhneia Sperm .... 



The Seasonal Infestation of Xassa obsoleta 

 (Say i ic i tli La real Trematodes .......... 



Correlations and Variability of the Central 

 Nervous System and Body Si~e of tin 

 Albino Rat ........................... 



444 



4=0 



400 



50') 



The Nutrition of the Ovum of Hydra viridis 5 



PUBLISHED MONTHLY BY THE 



MARINE BIOLOGICAL LABORATORY 



PRINTED AND ISSUED BY 



LANCASTER PRESS, INC. 

 LANCASTER, PA. 



AGENT FOR GREAT BRITAIN 



WHELDON & WESLEY, LIMITKD 



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Single Numbers, S1.0O. Per Volume <6 numbers), 4.50 



Entered October 10, 1902, at Lancaster, Pa., a? second-class matter under Act of Congress of July 16. 1804 



