Order SYNENTOGNATHI Gill. 



Airbladder without an open duct. Scales present, cycloid. 

 Lateral line present, running low down. Parietals, when present, 

 very small, separated by the supraoccipital. Orbitosphenoid 

 absent. Mesocoracoid arch absent. Opercular bones normally 

 developed. Lower jaw with a sesamoid articulare. Fins without 

 spines. Pectorals inserted very high up. Pectoral arch suspended 

 from the skull. Ventrals abdominal, 6-rayed, not attached to 

 cleithra. Dorsal fin placed far back, totally or partly opposite 

 to anal. Anus posterior. Anterior vertebrae not modified. Mouth 

 small or large, bordered by intermaxillaries and maxillaries. 

 Lower pharyngeals completely united into one plate. Bran- 

 chiostegals 9 — 15, 



Key to the su bo r d e rs o f Sy n en t og n at h i. 



1. Mouth large, the jaws usually produced. Scales small. 



Third upper pharyngeals separate, fourth usually present. Scombresocoidca p. 115. 



2. Mouth small, only the lower jaw sometimes produced. 

 Scales lai'ge or moderate. Third upper pharyngeals 



united, fourth absent Exococtoidca p. 134, 



L Suborder Scombresocoidea. 



Scales small. Mouth large, the jaws usually produced and 

 narrowed forwards, forming a slender beak. Maxillaries firmly 

 united to intermaxillaries. Rami of the lower jaw united through 

 the interlocking of a series of inner processes, which form a 

 more or less roughened ridge between them. Teeth very small, 

 in a series in the jaws or in bands, accompanied by a single 

 series of large teeth. Third upper pharyngeals moderately 

 enlarged, separate; fourth usually present; lower pharyngeal 

 triangular or long and narrow. Pharyngeal teeth usually villi- 

 form or granular, some of the teeth of the principal plates 

 often compressed, tricuspid. Parasphcnoid without apophysis. 



