NATURAL SCIENCES OF PHILADELPHIA. 243 



respects it is most nearly allied to the Prionurus laticlavius Val., from the 

 Gallapagos Islands. 



Family CHsETODONTOIDJE. 



Subfamily CH.ETODONTINiE. 



Genus Sarothrodus Grill. 



Sarothrodus nigrirostris Gill. ' 



The body is elevated, the height being nearly equal to three-fifths of the 

 extreme length. The snout is little produced, and shorter than the diame- 

 ter of the eye. The pectorals equal the head's length, and are scarcely longer 

 than the ventrals. The lateral line is slowly curved upward as far as the 

 vertical of the fourth soft dorsal ray, and is there nearly parallel with the back, 

 from which it is mostly separated by an interval equal to the width of the in- 

 terorbital area. 



D. XII. 24. A. III. 20. 



Scales lat. line 44. 



The ground color is apparently light and uniform. The head is whitish ; 

 the muzzle has a blackish band ; there is a transverse interorbital band emar- 

 ginated behind and much narrower than the orbit. A band between the dor- 

 sal fiu and the interorbital area descends to the temples and is bordered by 

 whitish. Another obliquely crosses the dorsal fin, caudal peduncle and near 

 the margin of the anal, the anterior margin of which extends from the base 

 of the anterior soft rays to the axilla of the anal fin ; the band is bordered by 

 whitish. The caudal, the produced portion of the dorsal, margin of the 

 anal, and all the pectoral and ventral fins appear to have been uniformly 

 light. 



This species is allied to Sarothrodus uli e t e lis i s (Chastodon ulietensis 

 Blkr.) S. robustus(C. robustus Gthr.,) S. humeralis(C humeralit 

 Gthr.) S. gracilis, ( C. gracilis Gthr.,) and S. m ac ul o-c inc tu s Gill; 

 but is readily distinguished by the above diagnosis. 



Two specimens, about two inches and a half long, were sent by Mr. Xantus 

 to the Institution ; the alcohol having evaporated, both have been dried up. 



Genus Holacanthus (Lam. ) C. et V. 



HOLACANTUUS STRIGATCS Gill. 



The greatest height exceeds two-fifths (-43) of the length. The length of the 

 head forms almost a quarter (-24 ;; the diameter of the orbit equals a third 

 (08) of that length, and is less than the length of the snout (=-09,) and greater 

 than that of the preopercular spine (-07.) The margin of the dorsal and anal 

 fins are slightly convergent backwards ; the angle of the former is little acu- 

 minate, and passes beyond the anterior half of the caudal, the longest rays 

 nearly equalling the head's length ; the anal angle is obtuse or slightly 

 rounded. The caudal is scarcely convex, and slightly oblique, its upper 

 angle passing beyond and less blunt than the lower ; the length is less than 

 a fifth (-19) of the total. The pectoral exceeds a fifth (-21) and the ventrals 

 nearly equal a quarter ("24) of the total length. 



D. XIV. 17. A. III. 16. 



The color is dark purplish brown, crossed below the seventh spine by a 

 whitish band attenuated and curved backwards below ; four nearly equidis- 

 tant indistinct vertical bluish lines cross the body between the band and the 

 base of the caudal. The head is girdled with two broader and more distinct 

 bluish bands, one in front of the eyes, and the other in front of the dorsal and 

 behind the eyes. The dorsal and anal have two indistinct lines parallel with 

 the borders, and the posterior margins are also bluish. The pectorals, 

 dorsal and caudal are yellow ; the latter alone margined with brown. 



1862.] 



