GILBERT AND STAKES — FISHES OF PANAMA BAY 149 



nostril. A black blotch above and behind each orbit, fails to meet its fellow by a 

 distance about equaling the diameter of the pupil. A narrow black orbital ring 

 encroaches on the eye-ball. A wedge-shaped black bar has its apex at front of 

 dorsal, its base being separated from the orbital region by a transverse whitish bar 

 which crosses the head behind the eyes. The wedge-shaped bar is bordered behind 

 by a wide silvery band. The opercular membrane is jet-black, as is also the mem- 

 brane covering the shoulder girdle. A few of the scales covering the supraclavicle 

 are edged or blotched with black. A jet-black bar crosses the base of the upper 

 three-fourths of the pectoral, and is continued into a broader axillary band, which 

 likewise fails to involve the lower rays. A broad black bar begins at base of fifth or 

 sixth dorsal spine, includes the basal half of soft dorsal and is continuous with a 

 wedge-shaped bar on caudal peduncle, the apex of the wedge failing to reach the 

 lower edge of the peduncle, but directed toward the margin of the last anal rays. 

 The remainder of the vertical fins are ti-anslucent dusky, unmarked. The ventrals 

 are dusky; the pectorals translucent yellowish. 



We have not admitted to our list the Atlantic species Chcetodon capistratus. 

 recorded without comment from Rio Tuyra, Darien, by Boulenger (1899, p. 3). 



278. Chaetodon humeralis Oiinther. 



The young are abundant in tide-pools, and adults are present in large num- 

 bers among the rocky reefs and islands in the Bay. 



Our youngest specimen is 28 mm. long, and is in the last phases of the 

 " 2'holichthys" stage. The color scheme of the adult is plainly indicated, but the 

 head is wholly scaleless and is entirely covered with sculptured shields. One of these 

 extends from the occiput on to the nape, in the form of a dagger-shaped spine, which 

 fails to reach front of dorsal by a distance equaling about one-fourth its length. The 

 angle of the preopercle is produced into a rounded squamous process, which extends 

 more than half way to the insertion of the ventral fins. Two similar squamous lobes 

 are attached to the upper portion of the shoulder girdle, their posterior margins 

 being free. The upper is larger and less evenly rounded than the lower, and is 

 separated from it at the point traversed by the lateral line. The margins of these 

 lobes and the preopercular margin are very finely but sharply serrulate. Similar but 

 smaller squamous processes are attached to the horizontal limb of the preopercle and 

 to the inner edge of the dentary, lobes on one side of the head corresponding to inden- 

 tations on the other, those of the two sides closely joining below and wholly concealing 

 the isthmus and the brauchiostegals. The cheeks are firmly cuirassed, like the rest 

 of the head. 



The colors are the same as in adults with these exceptions: The ventrals are 

 black. The vertical black bar at base of caudal is faintly indicated. The caudal 

 fin, and the soft dorsal and anal fins are translucent, unmarked, thus contrasting 

 strongly with their barred condition in the adult. The broad bar across posterior 

 portion of trunk is continued definitely on to posterior portion of spinous dorsal, and 



(20) December 22, 1903. 



