152 



PAPERS FROM TORTUGAS LABORATORY vol. xxxiv 



Pomacanthus aureus (Bloch). Black angelfish 



(Plate 22, figures 1,2) 



Chactodon aureus Bloch, Naturgesch. ausland. Fische, vol. 3, 1787, p. 49, pi. 193, fig. 1 — 



Martinique (on a drawing by Plumier). 

 Chaetodon luteus Bonnaterre, Tab. encyc, Ichth., vol. 6, 1788, p. 88, pi. 92, fig. 381 (after 



Bloch). 

 Pomacanthus baltcatus Cuvier and Valenciennes, Hist. nat. poiss., vol. 7, 1831, p. 156 — 



Puerto Rico. 

 Pomacanthus rathbuni Miranda Ribeiro. Arch. Mus. nac. Rio de Janeiro, vol. 17, 1915 



(Chaetodontidae, p. 7), with fig. — Bahia, Brazil. 



Bloch's figure of Chaetodon aureus poorly represents a species of Pomacanthus, 

 as is shown by the armature of the preopercle and contours of the posterior 

 borders of dorsal and anal fins. The form of the caudal more closely approaches 

 that of P. arcuatus than that of this species, but the dorsal spines are too many 

 for either. From examination of the plate alone, one might hesitate to say which 

 of the two had been drawn. Cuvier and Valenciennes, however, stated that this 

 figure is a poor copy of Plumier's first sketch, of which they had seen a better 

 one by Aubriet representing one of Parra's Chirivitas (Desc. dif. Piezas hist, nat., 

 1787, pi. 6, fig. 2). If they are in error in their identification, aureus is a synonym 

 of arcuatus and the species here discussed is P. balteatus. 



This species is much more common than P. arcuatus, and possibly most com- 

 mon of Tortugas angelfishes. It may be seen singly or in pairs in shallow water 

 on the open reef throughout the group. The largest individuals that still display 

 the juvenile coloration are the most numerous. 



Young to perhaps the length of 175 mm. show a pattern of five or six narrow 

 yellow bars on a dark brown or blackish ground. The first cuts off a rostral dark 

 spot about the mouth; the second meets its fellow on the nape and before the 

 pectorals; the third defines posteriorly a humeral bar and extends on dorsal, and 

 ventrally ends just before anal origin; the fourth bar crosses body between 18th 

 dorsal and 12th anal rays, extending on dorsal and anal; and the fifth bar covers 

 basal third of caudal and its borders above and below. Posterior margin of the 

 caudal, transparent at first, may develop into a sixth bar, enclosing with the fifth 

 one a dark lenticular spot. Posterior face of the pectoral citron yellow; posterior 

 border of dorsal narrowly yellow, anal narrowly blue. 



As the fish grow, the yellow bar on the base of the caudal becomes gray and 

 eventually disappears, but the one bordering the truncate caudal remains. The 

 bar behind the pectoral is last to disappear. Transformation is effected at no con- 

 stant size, for specimens in full adult coloration may be seen with others an inch 

 or two longer, still showing their last gray bar or bars. 



The diet includes algae and a great variety of sedentary animals. 



Atlantic coast of tropical America to Florida, sometimes straying northward. 



W. H. L. 



Holacanthus tricolor (Bloch) 



Chaetodon tricolor Bloch, Naturgesch. ausland. Fische, vol. 9, 1795, p. 103, pi. 426 — Cuba. 

 Sarothrodus ataeniatus Poey, Repertorio, vol. 2, 1868, p. 353 — Cuba. 



