IV <>\ I ENTS <>! VOI.TMK L. 



No. 6. Ji \K, K)jr>. 

 PAYNE, FERNANDUS. Further Studies on the Life I/is/nrv of 



Craspedacusta ryderi, a Fresh --icatcr Hydromedusan 



BECKER, ELERY RONALD. Endama'ba citeUi sp. nov. from 



the Striped Ground Squirrel Citellns tridecemlineatus, 



and the Life-History of its Parasite, Splucrila endannvbx 



sp. nov 444 



HINRICHS, MARIE A. Modification of Development on the 



Basis of Differential Susceptibility to Radiation, III . . . . 455 

 HINRICHS, MARIE A. The Effect of Ultraviolet Radiation on 



the Fertilizing Power of Arbacia Sperm 47,} 



MILLER, HARRY M., JR. The Seasonal Infestation of Nassa 



obsoleta (Say) with Larval Trema lodes 490 



HAMMETT, FREDERICK S. Correlations and Variability of 



the Central Nervous System and Body Size of the Albino 



Rat 509 



KEPNER, WM. A., AND LOOPER. J. B. The Nutrition of the 



Ovum of Hydra viridis 525 



