128 Mr. 0. T. Resan on th 



•ie 



a fold across the isthmus, to which they are narrowly 

 attached. Mouth small, terminal, transverse, not protractile ; 

 jaws with bands of setiform teeth ; palate toothless. An 

 elevated occipital crest ; no parietal crests ; a subocular 

 shelf. Vertebrae 23 (10 + 13) ; last 3 prsecaudals with para- 

 pophyses ; ribs sessile, inserted high up on the centra or on 

 the bases of the neural arches. 



Fam. 42. Chaetodontidae. 



Body deep, compressed. Spinous dorsal well developed; 

 soft dorsal and anal densely scaly ; anal spines 3 or 4 ; 

 caudal of 17 principal rays, 15 branched; pelvic axillary 

 process present. Gill-membranes sometimes united, but 

 i'ree from the isthmus, more often narrowly attached to the 

 isthmus. Mouth small, terminal, protractile; jaws with 

 hands of setiform teeth; palate toothless. An elevated 

 occipital crest : no parietal crests ; a subocular shelf. 

 Vertebrae 24 (10 + 14); prsecaudals with transverse processes; 

 ribs much expanded proximally, inserted on the transverse 

 processes, with which they form an extended articulation. 



Principal genera : Chcetodon, Chelmo, Heniochus, Hola- 

 cmithus, Pomacanthus. 



Fam. 13. Enoplosidae. 



Enoplosvs appears to be at least as closely related to the 

 Histiopteridae as to the Scorpididse. It resembles the llistio- 

 pteridae in the large pelvic tins with long and strong spines 

 placed below or slightly behind the pectorals, the short 

 and broad pelvic bones, the occipital crest with the anterior 

 edge thickened, the absence of parietal crests, &c. Mouth 

 normally formed ; maxillary exposed distally, with supra- 

 maxillary ; villif'orm teeth in jaws and on vomer and 

 palatines; praeorbital normally attached to lateral ethmoid, 

 forming part of the border of the orbit ; a subocular shelf. 

 Vertebrae 26 (10+16); prsecaudals with parapophyses from 

 the fifth ; ribs, except the last pair, sessile. 



Fam. 44. Histiopteridae. 



Differs from the preceding especially in that the praeorbital 

 is displaced forward, not entering the orbit, and in the 

 vertebral column, which comprises 25 vertebras (13 + 12), 

 the prsecaudals with parapophyses from the fourth or fifth, 



