GREGORY: FISH SKULLS 



301 



That the most primitive acanthopterygians had a short vertebral column of ten ab- 

 dominal and fourteen caudal vertebrae was the suggestion of Boulenger, which finally pro- 

 vided the clue to many of the puzzling facts recorded by Gill, Jordan and others (see 

 Jordan, 1891, pp. 202-216). Smith Woodward also" records this number in several Cre- 

 taceous acanthopts, including the berycoids Hoplopteryx and Aipichthys, Vomeropsis, Mene, 

 which he refers to the Carangidse and which Tate Regan refers to the Berycoidea. Boulen- 

 ger's family definitions of Carangidse, Scombridse and related families show the more 

 primitive numbers (24—26) in Carangidae, the higher numbers (30—50) in Scombridse and 

 the extreme (32-60) in the progressively long-bodied Gempylids and Trichiuridae. Even 



epict 



Pomatomus saltatrix 



Fig. 177. Pomatomus saltatrix. 



without material increase in number, the lengthening of individual vertebrae causes a pro- 

 gressive increase in body length in the various species of the genus Seriola. As regards 

 the fins, the allied genus Trachinotus is the most nearly ovate to orbicular species. Trach- 

 inotus falcatus (Fig. 178) and T. culveri (see Meek and Hildebrand, 1925, Pis. XXXIII 

 and XXXV, pp. 378, 381), have the obviously least specialized condition of the dorsal 

 and anal fins, while in the related but longer-bodied genus Oligoplites {Scomberoides) the 

 spinous dorsal and anal are either reduced or separated from the soft-rayed parts of the 

 fin. In Oligoplites rejulgens (Meek and Hildebrand, 1925, PI. XXXIX) the body has be- 

 come almost mackerel-like in its length and slenderness. Aleanwhile the head has also 

 become more elongated, the opercular broadening antero-posteriorly. Even in these 

 elongate forms the lateral line retains the great curve above the pectoral fin which is char- 

 acteristic of the ancestral ovate to orbicular body-form of the Carangidae. 



Again, if we study the vertebrae and ribs it will be seen that the carangoids are in- 



