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BULLKTIN OF THE UNITED STATES FISH COMMISSION, 
EXPLANATION OF PLATE XLII. 
Fig. 18. Side view of the jiist-hatched larva of the common sturgeon on the sixth day after the eggs 
were fertilized. There is a large cavity at the front of the yelk-sack in which the heart lies 
at this stage. A simple Cuvierian venous duct embraces the front end of the yelk, and ex- 
tends from a point just a little in front of the still exceedingly rudimentary pectoral fin to 
the ventral side of the yelk. The tail is lanceolate in form and lophocercal in structure. 
There are no barbels, and the larva is now 11^“™ long, or more than twice the length of the 
just-hatched sterlet. The figure is sixteen times natural size. 
