Classification of the Pereoid Fishes. 131 



or very narrow. Occipital crest short, not prominent; no 

 parietal crests. Vertebrae numerous, 65—100, equaJ in uumber 

 to the dorsal raya (in C. rubescens 15 + 54); praecaudals 

 with par apophyses from the eighth ; ribs on parapophyses 

 when these arc developed. 



1 h in i'a : ( 'epola and . [canthocepola. 



The Cepolidae arc aberrant Serranidae, and differ from that 

 family in little but the absence of spinous rays in the 

 vertical tins, the reduced caudal, the elongate form, and in- 

 creased number of vertebrae. 



Division 2. Cirkhitiformes. 



I have already dealt with this group in a separate paper 

 (Ann. & .Mag. N. II. (8) vii. 1911, pp. 259-282). 



The "pharyngognathous" fishes of the order Percomorphi 

 form three well-marked and probably not specially related 

 gronps, which resemble each other in the ankylosis of the 

 lower pharyngeals to form a single bone. "Were it not for 

 this all three would be included in the division Perci formes, 

 since their external and anatomical characters are those of 

 typical perciform fishes. 



Division 3. Ditremiformes. 



Lower pharyngeals ankylosed to form a triangular plate ; 

 second upper pharyngeals absent, third and fourth united. 

 A subocular shelf. A single postcleithrura on each side. 

 Vertebrae 3.2 to 42 (13-19 + 19-23); first centrum rigidly 

 united to skull; ribs sessile, attached to the centra above 

 the parapophyses. Two nostrils on each side. Four gilis. 



This division includes but a single family, Ditreinidse, 

 viviparous shore-fishes of the North Pacific. 



Division 4. Po.macextriformes. 



Lower pharyngeals ankylosed to form a snbtriangular 

 plate ; second upper pharyngeals distinct, third and fourth 

 united. A subocular shelf. Two postcleithra on each sale. 

 Vertebrae 26 (11 + 13) ; first centrum normally articulated 

 with skull ; ribs inserted in sockets at the disti 1 extremities 

 of transverse parapophyses. A single nostril on each side. 

 3J gills. 



This division also includes but a single family, the Poma- 

 centridae, littoral fishes of warm sei 



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