CHAP. XXIII 



ACANTHOPTERYGII 



6 5 I 



a 



Ophidiicfoz 



fiEMOSOM/ 



HAPLOM 



FIG. 399. Diagram showing probable relationship of the various groups to one 



another. 



Primary shoulder-girdle composed of a perforate scapula and a coracoid ; of 

 the four or five pterygials, or basal bones of the pectoral fins, only one or 

 t\vo are in contact with the coracoid ; ventral fins thoracic. 

 Rays of the caudal fin not strongly forked at the base ; hypural usually 

 with a basal spine or knob-like process on each side ; epipleural bones 

 usually inserted on the parapophyses or on the ribs ; dorsal fin usually 

 with strong spines ; caudal peduncle rarely much constricted 



I. PERCIFOUMES. 



Rays of the caudal fin strongly forked at the base, embracing a considerable 

 portion of the hypural, which always bears a basal spine ; epipleural bones 

 usually inserted on the centra or on the parapophyses, rarely on the ribs ; 

 dorsal spines feeble or detached ; caudal peduncle much constricted ; 

 scales usually very small or absent . . .11. SCOMBRIFORMKS. 



