i6 



BULLETIN OF THE BUREAU OF FISHERIES. 



After the closure of the blastopore the embryo increases in length until it extends 

 more than two-thirds around the greater circumference of the yolk (fig. 36). In some 

 instances, before the time of hatching, the embryo extends entirely around the circum- 

 ference of the yolk. 



Larval development. — The time required for hatching, as already indicated, is 

 approximately 24 hours. Hatching usually occurs between 6 and 9 o'clock p. m. The 



-9r 



ANCHOVIA MITCHILLI. 



Fig. 29. — Egg with blastoderm, showing early germ 

 ring (pr). X 60. 



Fig. 30- — Egg with blastoderm showing fully de- 

 veloped germ ring ((jr) and beginning of em- 

 bryonic shield i,es). X 60. 



newly hatched larvae (fig. 37) are 1.8 to 2 mm. in length. The yolk sac, which remains 

 comparatively large, is greatly elongated and tapers to a point posteriorly. The seg- 

 mented character of the yolk, already noted in the egg, is still apparent. The head of 

 the young fish is deflected at the anterior end of the yolk sac. The body is appreciably 

 flattened and comparatively slender. The fin folds are continuous. The depth of 



$K ; 



ANCHOVIA MITCHILLI 



Fig. 31. — Egg showing advanced stage in develop- F1G.32. — Same as figure 7. lateral view; pr, germ 



mentof embryonic shield {es), embryonic area (ea) ring. X 60, 



outlined. X 60. 



each fin fold is less than the depth of the bod}'. The lan-al fish is almost perfectly 

 transparent and shows no evidence of pigmentation. 



At 12 hours after hatching (fig. 38) the larval fish has grown to a length of 2.6 to 

 2.8 mm. The remaining yolk mass retains its elongated form and its segmented character. 

 The head of the young fish is no longer deflected. 



The yolk sac decreases in size until at 15 to 18 hours after hatching it is completely 

 absorbed. For some time after the yolk is absorbed the lar\'al fishes increase in size 



