II04 BULLETIN OF THE BUREAU OF FISHERIES. 



tails are more frequently still than in motion, while the pectorals keep up a slow 

 but continual fanning motion, broken at intervals by a few impatient strokes. 



Figure ii, plate cxii, is an instantaneous photograph (natural size) of the 

 nest shown in the preceding and in other photographs. Here the young are 

 ready to break away. They are in continual motion, lashing with their tails, 

 swinging back and forth, even twisting in their efforts to break loose from their 

 anchorage. This is apparent in the figure in the blurred effects, which are due 

 to the motion of the little fish while the plate was being exposed. While one is 

 looking one or more little fish may break loose and swim rapidly away, seeking 

 at once a place of safety under the board or in holes in it. As best I can deter- 

 mine, at Beaufort detachment is effected twenty-four to twenty-six days after 

 fertilization. An allowance of two or three days must be made for variations 

 in the temperature of the water, the degree of virility of each little fish, and 

 external stimuli, such as fear or some mechanical shock, exciting the larvae to 

 greater action. Ryder (1887) approximates the fixed condition at from three to 

 four weeks at Cherrystone, Va. At Woods Hole the young became free in 1906 

 on the forty-second day, according to Patterson's notes forwarded to the writer 

 by Osburn. 



I am satisfied that these larvae begin to feed before they detach themselves 

 from the nest. Small Crustacea, and indeed anything which would serve as food 

 for them, would be drawn into their mouths by the action of the opercula and, 

 being caught by the gillrakers, would be passed down their gullets to the stomach. 



A curious phenomenon found only, so far as the writer's knowledge goes, in 

 the young of the toadfish, must now be described. The egg remains spherical 

 so long as the egg membrane exists intact, but immediately after the larva bursts 

 this the yolk begins to elongate and presently a constriction appears. This con- 

 striction appears at first to be due to the yolk pouring over the torn shell, but as 

 time passes and the shell is burst wide open, it is apparent that it is due to other 

 causes. 



Before going into the explanation of this curious constriction, it will be 

 proper to give a fuller description of the phenomenon itself. On looking at some 

 eggs but a few hours after hatching, at say 5 p. m., to make a hypothetical case, 

 we find the little embryo sitting on top of the rounded yolk ; some hours later we 

 find it on the summit of a pyriform eminence, to use Ryder's (1887) expression; 

 next morning we may find the yolk-sac still elongated but having a slight con- 

 striction at or near the middle (like a pillow or bolster with a rope tied around 

 it) , or drawn out into a pillar-like body sometimes as long as or even longer than 

 the embryo itself. Later still the yolk may round up and then again go through 

 the same series of changes described above, not necessarily, however, in the same 

 sequence, but with the order perhaps varied or some steps in the series omitted. 

 The changes in form of the yolk bag are, however, more or less rythmical. 



