U. S. B. F.— Doc. 890. 



1. 



Plate III. 



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A 



F1G.1. — SPERMATOZOON OF MALE OYSTER. Magnified 1 ,700 diameters. (AfterStafford.) 



FIG. 2. — OYSTER EGG. Magnified 600 diameters. 



FIG. 3. — FREE-SWIMMING LARVA OF OYSTER, ABOUT 10 DAYS OLD. Magnified 



300 diameters. 

 FIG. 4.— FREE-SWIMMING OYSTER LARVA WITH VELUM, OR SWIMMING ORGAN 



EXTENDED. Magnified 300 diameters. 



(Figs. 2, 3, and 4 drawn by J. S. Gutsell.) 



