] ( » lie V ie w of t/i e Ch te todouf idea 



CENTiic)PY(iE Kaup, Wiegm. Arch... XXVI, 1, 1876, Vdii {tibicen). 

 PoMACAKTHODES Gill, Proc. Acacl. Kat. Sci. Phila., 1862, 2^^ {zoni pectus). 

 AcANTHOCH^TODox Bleeker, "Arch. Iseerl. Sc. Xat., XII. 5," 1^1% {Itpi- 



dolepis). 

 Ch^todon Bleeker, 1. c. (transferred to species of Foinucanthtis, as the first 



species of Clmtodou mentioEed by Artedi Lelongs to the latter group). 



Type/ Pomacmithus grison. 



Lacepede based his genera Pomacantlius and Holacantlius on 

 tlie armature of the preopercle. This character is not sufficient 

 to separate the species of this gi'oup into two genera, because, 

 1st : The armature varies in the species of Holacanthiis from 

 minute serrae (passer and tricolor) to a number of strong spines 

 (ciliaris) ; 2nd : The upper limb of the preopercle, in the young 

 at least of some species otherwise resembling Pomacaritlius {zoni- 

 pectus), is armed with minute serrae. We have therefore placed 

 those species having a spine at tbe preopercle and the dorsal 

 si)ines graduated, in the genus Pomacanthus, regardless of the 

 armature of the upper limb of the preopercle. The degree of 

 ihe graduation of the dorsals might offer some distinctive char- 

 acters ; the species of Pomacantlius proper, having each succeed- 

 ing spine decidedly higher than the one preceding it. But here 

 again we find variation in the species of Holacanthus : the spines 

 of H. tricolor are all of about the snme bight, Avith the excep- 

 tion of the last two or three, while in II. ciliaris the spines are 

 regularly graduated, though the last si)ine does not attain the 

 bight that the spines in the species of Pomacantlnis do. The 

 subdivision adopted by Dr. Giinther, although natural enough, 

 does not seem very scientific, — the species with 8 to 10 spines 

 being placed in Pomacantlius, Avhile those with 12 or more con- 

 stitute the genus Holacantlius. One s})ecies properly belonging 

 to the former group has 11 spines. 



ANALYSIS OF NORTH AMEKICAN SPECIES OF POMACANTIU'S. 



<i. Dor)i(d f<puies S to 11 ; dorsal r((ys 23 to 32 ; sades of different size, the loti_ 

 git II di rial and cross series not distinct, 

 b. Scales of the lateral line 50- to 55. Dorsal spines 9 (rarely 8) ; soft rays SO 

 to 32 ; ancd rays III. 24. Color in the adnlt steel-yray. The 

 larger scales surrounded by smaller ones ; each scale with a 

 dark spot at l)ase ; older specimens nearly plain yellowish, 



