150 CALIFORNIA ACADEMY OF SCIENCES 



on to the basal portion of anal spines. There is at no time any ocellus, but a distinct 

 intensification of the black of the posterior bar occurs over a small rounded area 

 immediately below the last dorsal spines. 



With increasing size, there appears first the black bar on dorsal and anal, 

 contemporaneously with the broadening of the bar on caudal peduncle. A definite 

 white bar then forms behind the latter, on the basal portion of the caudal fin. Before 

 the sharp diflerentiation of this bar, white pigment occupies its future position, but 

 covers a wider area, gradually thinning out posteriorly, visible on the entire basal 

 third of the fin. As soon as it becomes concentrated into a narrow bar, a faint dusky 

 margin develops posteriorly, this widening to form a bar, which develops most rapidly 

 on the lower half of the fin. The bars on dorsal and anal are at first near the middle 

 of the fin, leaving a wide translucent margin, but later migrate distally. 



The largest of our immature specimens is 55 mm. long. At this stage, the 

 middle dark caudal bar is still much narrower than the basal bar, and there is no 

 trace of the succeeding two bars (white and black). 



279. Pomacanthus zonipectus (Gill). 



Much less abundant than Holacanthus passer, with which it was found asso- 

 ciated. But two individuals were seen. 



In adults, the upper profile is continued forward in an even curve to front of 

 nape. From this point, the occipital region is deeply concave, the profile becoming 

 again convex above ocular region and snout. The color has been well described 

 by Dr. Jordan (1895 h, p. 484) from Mazatlan examples. 



An immature specimen, 63 mm. long, shows the characteristic coloration of 

 the young, which has been described by Jordan and Gilbert (1881 c, p. 358), under 

 the name Pomacanthus crescentalis. The third yellow band behind the head cuts 

 the bases of soft dorsal and anal fins three or four rays in advance of the posterior 

 ends, instead of running from end to end, as described. It curves forward on the 

 two fins, meeting the anterior yellow band to form a broad loop, which is wider than 

 the bands and blue in color. The dorsal continuations of all save the caudal band 

 are blue. A blue bar is present midway between the first and second, and the second 

 and third yellow bars behind head; no other blue bars are present. The basal two- 

 thirds of the caudal fin is jet-black, save for the narrow vertical yellow bar which 

 divides that area equally. The outer third is translucent, with a narrow dusky bar 

 near the anterior edge of the tract. 



280. Holacanthus passer Valenciennes. 



Abundant among rocky islands in Panama Bay. 



Gill's type of H. strigatus, a synonym of H. passer, must have been an imma- 

 ture specimen. In such we find a conspicuous narrow blue streak running from nape 

 to upper posterior margin of orbit, thence faintly downward in a broken line toward 

 base of preopercular spine. This streak disappears entirely in adults. In the young. 



