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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
EXPLANATION OF PLATE XXXVIII. 
Fig. 6. Egg of sterlet with the large yelk cells nearly included by the embryonic membranes. The em- 
bryonic area and medullary groove is distinctly defined. After Salensky. 
Fig. 7. Still more advanced embryo of the sterlet, showing the medullary groove closing in the median 
line, and the blastopore at the lower pole. After Salensky. 
Fig. 8. Dorsal surface of still more advanced embryo of sterlet. Cerebral vesicles differentiated, while 
the Wolffian ducts and five somites or segments of the trunk of the embryo are visible. 
After Salensky. 
