Jordan and Evermann. Fishes of North America. 781 



PEUCESOCES: Ventral fins abdominal, each of 1 spine arid 5 rays; dorsal spines few, usually form- 

 ing a separate flu ; gill structures and structure of mouth normal ; the tail diphycercal. 



AMMODYTOIDEI : Ventral fins wanting ; no spines in any of the fins. Otherwise essentially as 

 in the Percesoces. 



KHEGNOPTERI : Pectoral actinosts not alike in form or position, 2 of them normal, supporting the 

 fin, 1 longitudinal without rays, 1 a plate on the coracoid supporting 3 to 10 free elongate rays, 

 separate from the rest of the fin; ventral fins subabdominal. Otherwise essentially as Percoidei. 



BERYCOIDEI : Ventral fins thoracic, typically with 1 spine and more than 5 soft rays. Spines of 

 fins various; squamation various; air duct sometimes persistent; tail diphycercal. 



SCOMBROIDEI : Ventral fins thoracic, typically with 1 spine and 5 soft rays; spines of fins various; 

 caudal peduncle typically slender, with abroad, strongly forked caudal fin; scales typically small 

 and cycloid, but often wanting or bony, or even ctenoid; shoulder girdle normal; gills normal; 

 tail diphycercal. 



PERCOIDEI : Ventrals thoracic, with 1 spine and 5 rays (rarely I, 4); lower pharyngeals separate 

 (very rarely coalescent); gills 4, a slit behind the fourth; nostrils double on each side; scale.4 

 typically ctenoid, and usually well developed; post -temporal slender, divided at tip and not coossi- 

 fied with skull; bones of jaws distinct; pectoral actinosts normal; vertebrae 24 to 40; tail 

 diphycercal. 



SQUAMIPINNES : Post-temporal typically coossified with the skull; maxillaries normal; fins usu- 

 ally scaly; ventrals thoracic, typically with 1 spine and 5 soft rays; vertebrae 24 or fewer; tail 

 diphycercal. 



SCLERODERMI : Post-temporal undivided and coossified with the skull; maxillaries coossified 

 with the premaxillaries and dentaries with the articular; ventral fins reduced or wanting, the 

 pelvic bone very long; jaws with distinct, teeth; skin covered with scales or movable plates; 

 spinous dorsal present; vertebrae in reduced number, less than 24; tail diphycercal. 



OSTRACODERMI . As above, the body covered with bony immovable scutes, forming a carapace; 

 spinous dorsal obsolete; vertebrae in reduced number. 



GYMNODONTES : As in the Sclerodermi, the skin smooth or variously prickly or armed with plates; 

 no spinous dorsal nor ventral fins; teeth coalescent into 1 or 2 bony plates in each jaw; vertebrae 

 in reduced number. 



CIRRHITOIDE : Much as in the Percoidei, the pectoral very broad, its lower rays simple and 

 thickened. 



HOLCONOTI : Lower pharyngeals solidly united; young brought forth alive; anal fin very long; 

 scales cycloid; vertebrae more than 24. Otherwise essentially as in the Percoidei. 



CHROMIDES : Nostrils single on each side; lower pharyngeals completely united; gills3%or4, 

 the slit behind last gill present or absent. No labyrinthiform appendage to the gills. Other- 

 wise essentially as in Percoidei. 



PHARYNGOGNATHI : Nostrils double; lower pharyngeals fully united, without suture; gills 3%, 

 no slit behind the last; scales cycloid; ventrals thoracic, I, 5; bones of suborbital, jawe, and 

 shoulder girdle normal. Otherwise essentially as in Percoidei. 



CATAPHRACTI: Suborbital with a bony stay extending backward from the suborbital ring to or 

 toward the preopercle; nostrils double; lower pharyngeals separate; bones of jaws and shoulder 

 girdle normal; ventrals thoracic, often reduced, modified or wanting, always close together; pec- 

 toral fin simple; vertebrae usually more than 24; tail diphycercal. 



CRANIOMI: Suborbital, as in Cataphracti, the stay more developed; ventrals I, 5, widely separated 

 shoulder girdle peculiarly modified; the post-temporal forming an integral part of the skull, the 

 posterotemporal crowded out of place above and on each side of post-temporal; pectoral fin divided 

 in two parts or else with free detached rays. 



GOBIOIDEI : Ventral fins; thoracic, I, 5, typically close together or else united (sometimes widely 

 separated); the inner rays of each fin the longest; gill membranes broadly united to the isthmus; 

 dorsal spines few and weak; sott dorsal and anal long; scales various; nostrils, gills, jaws, subor- 

 bital, and shoulder girdle normal; vertebra- usually in small number (about 24); tail diphycercal. 



DISCOCEPHALI : Spinous dorsal modified into a lamellated sucking disk, placed on the back of 

 the head; ventrals thoracic, I, 5. Otherwise essentially as in the Trachinoidei. 



TRACHINOIDEI: Ventrals typically thoracic, with 1 spine and 5 rays, but often jugular or with 

 the rays reduced; nostrils, jaws, shoulder girdle, and suborbital normal; scales various; gills 3% 

 or 4; dorsal spines comparatively few; soft dorsal and anal fins long; tail diphycercal; an unde- 

 finable and probably heterogeneous group, its members provisionally left together. 



