Report of a Mission to Guam. 105 



slightly above the eye to the pe(5loral fins; this area is bounded 

 anteriorly by a blue line which extends down the middle and lower 

 edge of the opercle. A black area, margined with blue lines across 

 the forehead and over eyes like a mask; this black area, however, 

 does not extend down on preopercles, as in H. imperator, but the 

 blue borders unite direcflly behind the eye and send a vertical blue 

 line down to the base of the opercular spine. Four narrow oblique 

 blue lines on the thorax, and also a short blue cross line just back 

 of isthmus. Anterior of these are blue lines running from near the 

 base of opercular spine to the tip of the first ventral ray. A blue 

 line over the nape midway between first dorsal spine and black area 

 of forehead. Spinous dorsal and anal yellowish white; soft dorsal 

 blackish, the yellowish body lines forming a few reticulations in the 

 posterior part of the fin. Pe<ft;orals, ventrals and anal blackish, the 

 anal narrowly margined with blue, and with about three blue lines 

 running through it, forming reticulations in posterior part. This 

 species is closely related to H. impcrator (Bloch.), but differs 

 markedly from specimens of that species before me in the shorter 

 head and shorter preopercular spine, and the almost entirely differ- 

 ent markings of the body. One specimen. Length 4.50 inches. 

 This species was taken inside the coral reef, Agana, Guam, July 

 14, 1900. Type specimen is No. 193 in the B. P. B. M. Hab. 

 Marianas. 



193. Holacanthus nicobariensis Bl. 



Head 3.50; depth 1.50; D. xiv 20; A. in 19; eye 3.5 into 

 head, same as width of interorbital space. Preopercle serrated and 

 armed with a spine which is equal in length to the width of the 

 opercuhim. Teeth brush-like, much produced. Snout concave. 

 Fins: The posterior part of dorsal, anal and the caudal rounded; 

 dorsal continuous. Pectorals 1.16 into length of head, their bases 

 black crossed by one crooked blue line. Ventrals i 5, the first ray 

 produced into a short filament. Color: Black with curved, con- 

 centric alternating white and blue lines; four of these white lines 

 are especially wide and distinct, /. e., one running obliquely for- 

 ward just posterior to the eye — this touches the base of the pre- 

 opercle spine and runs out on the spines of the ventrals. The 

 second crosses the vent, curves up along sides of body, runs along 

 the base of the dorsal and ends in reticulations on the posterior part 

 of this fin. The third strongly marked white line extends in a deep 

 crescent from posterior base of dorsal to posterior base of anal fin. 

 The fourth and broadest line forms a complete circle around a short 

 straight white line just anterior of caudal peduncle. In addition 

 to these heavy white lines there is a lighter w^hite line midway 

 between each of them, and on each side of these narrow white 

 lines and midw^ay between them and the heavy w-hite lines, are 

 narrow concentric lines of blue. So, for example, beginning wdth 

 the heavv white line which crosses the vent, we have first the 



