I02 BULLETIN OF THE BUREAU OF FISHERIES, 



At this time the yolk is completely absorbed and the larval fish have grown to a length 

 of 2.8 to 3 ram. 



During the fourth day after hatching, larval fish kept in dishes of sea water began 

 to die rapidly. Few survived beyond the fifth day. The critical period comes some- 

 what earlier for this species than for Tautoga onitis. 



As the young fish grow older, one or more small pigmented areas appear dorsally 

 just posterior to the head, another on the dorsal aspect of the body opposite the one 

 on the ventral aspect and halfway from the vent to the tip of the tail, and one or two 

 very small areas at the base of the ventral-fin fold near the tip of the tail. These, in 

 addition to the pigmented areas shown in figure 26, are illustrated in figure 27 in a young 

 fish 4.2 mm. in length. 



In young fish 8 mm. in length (fig. 28) the distribution of pigmented areas remains 

 essentially as in the preceding stage. However, the two small areas which appear at 

 the base of the ventral-fin fold near the tip of the tall now appear at the base of the 

 caudal fin at the posterior end of the body. The dorsal, anal, and caudal fins are now 

 well differentiated and the young fish are gradually assuming adult characters. 



STENOTOMUS CHRYSOPS (Linnaus). SCUP. 



Spawning. — As is well known, this species spawns largely in June. The majority 

 of the fish taken after July i were spent. Eggs were not abundant in the plankton at 

 any time during July, but were taken in small numbers as late as August 15. 



Eggs. — The eggs are transparent, spherical in form, and 0.85 to 0.90 mm. in diameter. 

 The yolk sphere contains a single oil globule which normally rests at the upper pole. 

 The egg membrane is thin and homy. 



Embryology. — ^The embryological development of this species, like that of the 

 species above described, is entirely typical of teleosts with pelagic eggs. It conforms 

 so closely to the course of development as outlined above for Tautoga onitis that a 

 detailed description would be superfluous. The eggs being somewhat smaller than those 

 of the last-named species, development advances somewhat more rapidly. In water 

 at approximately 22° C. incubation occupied not over 40 hours. 



Pigmentation is first observed in embryos showing 15 to 20 somites. Black and 

 yellow pigment cells appear sparsely scattered over the embryo and the oil globule. 

 As development advances, these pigment cells become larger and more numerous. 

 In figure 31 yellow pigment on the embryo is indicated by coarse stippling, while the 

 black is shown in solid color. As the time of hatching approaches, the yellow 

 chromatophores become aggregated to form heavily pigmented areas. The extra- 

 embryonic blastoderm remains free from pigment. 



Larval development. — The newly hatched lan^ae (fig. 32) are approximately 2 mm. 

 in length. The head projects slightly beyond the anterior end of the yolk sac and is 

 not appreciably deflected. The oil globule remains in the posterior end of the yolk 

 sac. The vent is located a short distance from the posterior margin of the yolk sac, 

 but less than half the length of the body from the anterior end. Small groups of black 

 chromatophores remain sparsely scattered over the dorsal and dorsolateral aspects 

 of the body. The yellow pigment is distributed as follows: A few small areas on the 

 dorsal and lateral aspects of the head, a lateral area just posterior to the otocyst, a small 

 area above the vent, another opposite the vent on the dorsal aspect of the body, and a 



