44 MEMOIRS OF THE QUEENSLAND MUSEUM. 



The species examined are — 



Chcetodon ephippium C. & V. Queensland. 



octofasciatus Bloch. „ 



flavirostris Gunther. „ 



trifasciatus Park. „ 



ulietensis C. & V. Samoa. 



oricei Smith. Atlantic. 

 Heniochus chrysostomus C. & V. Queensland. 

 Chelmon rostratus C. & V. Queensland. 



SCALES OF POMACANTHIN.E. 



(1) The scales of Holacanthus and Chcetodontoplus are entirely of the same 



general type as those of Pomacanthus. (Cf. Bull. U. S. Bur. Fish., xxxii, 

 p. 167, f. 39.) 



(2) These scales are very different in their ctenoid area from those of the 



Chcetodontince, and taking this fact along with others, it may perhaps be 

 a question whether the Pomacanthince should not stand as a distinct family 

 Pomacanthidce. 



(3) Having in view the characters of related families, there can be no doubt, I 



think, that the scale-characters of the Pomacanthince are strongly modified 

 from the more primitive type of the group, which is much more nearly 

 approached by the Chcetodontince. The special modification is however 

 entirely in the ctenoid (apical) area. 



{4) Among the Holacanthinm, Holacanthus oicolor shows the nearest approach 

 to the chaBtodontine scales, having the lower (mesad) part of the ctenoid 

 area with small separate elements, instead of the usual continuous long 

 rods or ridges. There is some indication of this sort of thing in 

 Pomacanthus arcuatus. 



(5) Holacanthus oicolor, with its well denned converging basal radii, appears 



to approach a relatively primitive type ; but its ctenoid area, with long 

 parallel rods, seems extremely modified. There is a singular resemblance, 

 doubtless quite superficial, to the ctenoid area of Aphrododerus (Bull. 

 U. S. Bur. Fish., xxxii, p. 153, f. 13). 



(6) The Chaitodontoplus scale with its comparatively narrow form and rounded 



base is peculiar, but the ctenoid area agrees with that of H. oicolor. The 

 differences are much less significant than the resemblances. 



