496 WILLIAM K. GREGORY 



Superorder Acanthopteroidei 1 (nom. nov.) 

 (Plate XXIX.) 



The superorder Acanthopteroidei may be taken to include 

 the orders Percesoces, Anacanthini, Labyrintbici, Acanthop- 

 terygii, Selenichthyes (Inc. Sedis), Taeniosomi, Plectognathi 

 Hypostomides (Inc. Sedis.), Opisthomi, Pediculati. The air 

 bladder if present is without open duct (save in certain Bery- 

 cidae), the parietals are always separated by the supraoccipitals, 

 the mouth is usually "bordered by premaxillaries to the ex- 

 clusion of the maxillaries, and if these should by exception enter 

 the oral edge they are always toothless" (Boulenger). The 

 orbitosphenoids are typically absent (retained in Berycidae). 

 The pectoral arch, typically of the Perciform type, is suspended 

 from the skull (save in Opisthomi). There is no mesocoracoid. 

 The ventral fins, if present, are usually below or in front of the 

 pectorals. The pelvic bones, if present, are typically attached to 

 the clavicular arch either movably and by ligament in most 

 Percesoces and Nomeiformes or more firmly in Acanthopterygii 

 and the remaining orders. Fins usually with spines, ventral 

 fins typically with i spine and 5 soft rays. Scales various, 

 typically ctenoid. Vertebrae typically 10 + 14 but frequently 

 increased in number through "repetitive degeneration." 



The superorder Acanthopteroidei represents the highest 

 phases of piscine evolution or " ichthyization. " From the 

 swollen stream of central types realized in the Percesoces, the 

 short -bodied scombroids, zeoids, berycoids, percoids, by cen- 

 trifugal development many new types have been thrown off, 

 which constitute an irregular but less thickly crowded zone of 

 differentiation of the second degree, including such types as the 

 long-bodied Scombroids, the Squamipinnes or Chaetodontoids, the 

 Pharyngognathi or Labroids, the Pareiopliteae (Scorpaenids, 

 Cottlds Triglids, etc.) the Jugulares (Blenniids, Trachinids, etc.) 

 the Gobioids. Each of these in turn has become a new center 

 or vortex of differentiation and they have thrown off suclr'groups 

 as the Heterosomata, the Plectognathi, the Hypostomides, Disco- 

 cephali Opisthomi, Pediculati,which may be said to constitute'the 

 sparsely filled zone of differentiation of the third degree (PI. XXIX) 

 lAcanthopteri, ettfos, form. 



