38 SQUAMIPINNES. 



with a bluish border. Dorsal with a black basal band and two similar parallel ones 

 on the soft portion. Anal with three dark parallel bands and a brilliant blue margin. 

 Ventral with blue membrane between the spine and first ray. Pectorals black. The 

 markings disappear rapidly after death. 



Length 4^ inches. 



Zanzibar. 



116. Holacanthus trimaculatus. [4"3.] 

 Holacanthus trimaculatus, (Lacep.) Cuv. fy Val. vii. p. 196, pi. 182 ; Giinth. Fish. ii. p. 50. 



Zanzibar. Molucca Sea. 



117. Holacanthus imperator. [205.] 



Chtetodon imperator, Block, iii. p. 51, t. 194. 



Holacanthus imperator, Lacep. iv. pp. 527, 534, pi. 12. f. 3 ; Cuv. § Val. vii. p. 180 ; Giinth. Fish. 

 ii. p. 52. 



Zanzibar. Indian Ocean and Archipelago. 



118. Holacanthus semicirculatus. [599.] 



Holacanthus semicirculatus, Cuv. 1$ Val. vii. p. 191, pi. 183; Less. Voy. Coqu. Zoo/. Poiss. p. 173, 

 pi. 30. f. 3 ; Giinth. Fish. ii. p. 53. 



Zanzibar. East-Indian archipelago. Polynesia. 



119. Holacanthus altemans. [196, 216.] 

 Holacanthus alternans, Cuv. fy Val. vii. p. 193 ; Giinth. Fish. ii. p. 53. 



In old specimens [196] all traces of cross bands disappear, but the darker spots on 

 the head and body remain. 



The affinities between H. semicirculatus and H. alternans are of such a nature 

 as to call for a renewed examination of fresh specimens to settle the question 

 whether the differences between them are not dependent on sexual development 

 or age. Specimens with cross bands are 6 inches long, those without bands 10-| inches. 



Zanzibar. Aden. Madagascar. 



120. Holacanthus chrysurus. [52, 348.] 

 Holacanthus chrysurus, Cuv. &; Val. vii. 188 ; Giinth. Fish. ii. p. 54. 



n 1M? a -JL 



L'0-19" ^- 19-20" 



Immature specimens [52] have a broad yellow band from the last dorsal spine and 

 three first rays across the body nearly to the anal. 

 Aden. Zanzibar. 



