434 



TELE OS TBI 



number. The head is more or less completely covered with the scale- 

 bearing skin. Among the Chaetodontiformes are some of the most 

 specialised of Teleostean fish ; they diverge 

 greatly from the Perciform stock from which 

 they appear to have arisen. 



Division A. Squammipennes. These still 

 preserve many of the primitive characters : 

 there are a subocular shelf, ctenoid scales, 

 four gills, paired and median fins with spines, 

 and well -developed pleural ribs. The body- 

 scales extend between or over the dermal rays 

 of the median fins. They are probably more 

 closely related to Sub-Tribe B than to any 

 other Perciformes. 



Family Chaetodontidae. The body 

 becomes very compressed and deep, the mouth 

 produced forward, the 'face' more vertical, 

 and a very high supraoccipital crest is con- 

 tinued at the sides into the pterotic crest ; 

 it is enormously enlarged in Ephippus (Fig. 

 442) ; the minute setiform teeth are set in 

 bands. The opercular bones may be armed 



a.eSe.ae^ofTonfflnd^ with spines; in Holocanthus there is a pro- 



ot suiiraoceipitai ; ,-, intcrorbital minent preopercular spine. 



septum; d, basis cranii. (After nl . , . , ,-r,. , . „, „ , , 7 



Gunther.) Chaetodon, Art. (rig. 443); Holacantlius, 



Lac; Pomacanthiis, Lac; Ephippus, Cuv.; 



Platax, C. and V. (Fig. 444) — tropical seas ; Eocene, Europe. Ghelmo, 

 Cuv. ; Parapsettus, Stnd. 



Fig. 44-2. 



Fig. 443. 

 i haetodon ephippium, C. and V. (After Gtintlier.) 



Family Drepanidae. Very like the last, but having lost the sub- 

 ocular shelf, and with very long specialised pectoral fins. 

 Drepane, C. and V. ; Indian Ocean. 



