44 THE PELAGIC STAGES OF YOUNG FISHES. 



cells on the posterior edge of the globule, which may be regarded as an 

 extension of the ventral spot of the posterior (fourth) pair; and a single 

 spot, found on the median dorsal line opposite the third pair of spots, is not 

 shown in the figure. 



The arrangement of the yellow spots remains the same up to the time 

 of hatching (Fig. 8), by which time many of the cells composing the clusters 

 have passed from the rounded into the dendritic form. The yellow cells on 

 the globule are now scattered over its whole surface, and present both 

 stellate and rounded forms. A single yellow cell is seen in front of the 

 eye, and two finely branched black cells on the yolk-sac, none of which 

 were present in the earlier stage. The black cells are less numerous 

 than in the preceding stage, and are confined mainly to the dorsal angles 

 of the segments. The dorsal and ventral fin-folds, and the posterior half 

 of the tail, are not pigmented. The young fish is remarkably clear and 

 transparent, and remains so through all the subsequent stages we have 

 noticed. The ventral fold is broadly emarginate at a point a little behind 

 the yolk-sac, where the vent is found. 



The following measurements were taken from this stage: — 



Total length 2. .35 mm. 



Yolk-sac 85 " 



Yolk-sac to vent 125 " 



Vent to tip 1.50 " 



Width of head 35 " 



The yolk-sac is ovoid, the width of the larger end .525 mm. 



Two days after hatching, the black pigment forms a complete network 

 of delicately branched cells on the yolk-sac and oil-globule. Similar 

 branching cells are seen on the head in front of the eves, and two stellate 

 cells are placed at equal intervals between the third and fourth sets of 

 yellow spots. The black pigment-cells have diminished in number on the 

 body, and multiplied on the yolk-sac, where they are somewhat more numer- 

 ous than in the younger stage of another individual represented in Fig. 9. 

 The yellow spots now have a duller hue, and in other respects present an 

 aspect quite unlike that seen in the previous stage. 



The cells now blend in an irregular massive form, from which numer- 

 ous long, straight arms radiate in all directions, but with a marked pre- 

 ponderance to one side. The first spot clasps the posterior half of the 

 eye, as shown in Fig. 9 ; the second sends strands in all directions, the 



