134 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Figure 24. — Living prejuvenile Pseudopriacanlhus alius (estimated 50 mm.). 



those of the spinous part of tlie fin, were also 

 present in the pigment mass at the base of the 

 soft part of the fin. 



On a 40.7-mm. specimen (fig. 16), the fight 

 spots on the spinous part of the dorsal fin had 

 enlarged until there was only a suggestion of spots. 

 The membrane bordering the anterior edge of 

 each spine bore a line of dark pigment, and the 

 spines retained a few chromatophores. The 

 pigment mass near the base of the soft fin had 

 moved farther distally, and the membranes were 

 pigmented only at the base. The pigment mass 

 was broken up by light spots. Distal to the mass, 

 individual chromatophores were arranged in 

 irregular rows, along the ra.ys only, to the edge of 

 the fin. 



By 48.6 mm. (fig. 17), the spinous part of the 

 fin was essentially unpigmented, except for a few 

 scattered chromatophores near the anterior and 

 posterior edges of the membranes. Some of the 

 migrating pigment on the soft part of the fin had 



accumulated on the edge of the fin, particularly 

 at the ends of the most anterior ra3's, and the 

 chromatophores near the tips of the rays had 

 broken into a mass of snialler spots extending onto 

 the adjacent membranes. Of the original pig- 

 ment mass at the base of the soft fin, only scattered 

 chromatophores remained on the membranes and 

 bands of pigment on the rays. In the basal area 

 of the fin only the membranes retained pigment. 

 In a 58.9-mm. specimen (fig. 18) the lines of 

 pigment on the membranes, parallel to the spines, 

 were less intense, and all traces of the. light spots 

 on the spinous fin were gone. Some pigment 

 remained at the distal edge of the interspinous 

 membranes, especially on the most posterior 

 spines, connecting the spines with a thin dark 

 line. The basal half of the soft fin was inuuaculate 

 and only a few scattered migrating chromato- 

 phores remained proximal to the dark anterior 

 edge. The chromatophores on the posterior edge 

 of the fin had nearly disappeared. 



