^•''■-•v- • ■"^'.- 



''- ■ •'• V' 201 



apparent cartilaginous or fibrous core. Gill membranes broadly joined to isthmus at 

 a plane even with or behind the orbits. Branchiostegal rays displaced onto throat in 

 a fan-like fashion, covered by thick skin. 



Neurocranium very flattened, with relatively thin bones that often are highly 

 vacuous except in very large individuals. Frontals constricted along lateral margins, 

 forming medial border of orbit. Sphenotic relatively small, with a short 

 anterolateral projection at posterior position of infraorbital canal. Palatine broad, 

 plate-Uke. Nasals forked, each with an anterolateral accessory branch. Cranial 

 fontaneUe relatively large on upper surface, converging to a smaller posteroventral 

 opening above brain. Supraoccipital relatively flat and broad, weakly rugose; 

 strongly concave in nuptial males, posterior end strongly inflected upward at base of 

 dorsal fin. Accessory bone formed from modified second dorsal fin basal absent 

 from surface of nuchal shield. ■,- V 



Six anteriormost vertebrae fused to form Weberian complex. Anterior 

 parapophysis of fourth vertebra elongate, with triangular or oval plate-like tip 

 ( = MuUerian ramus), closely impinging on anterolateral face of swimbladder in 

 species with an unencapsulated swimbladder. Miillerian ramus of species with 

 encapsulated swimbladders relatively small. Anterior supracarinahs muscles 

 originating on ventral surface of supraoccipital and inserting on anterodorsal aspect 

 of Mullerian ramus, thereby forming an elastic spring mechanism (ESA). ' -^ 

 Swimbladder oval to pyriform-shaped, with posterior caecae in most species, and 

 either large and relatively turgid, or enclosed by bony capsules formed from 

 superficial ossification of the complex centrum. First pleural rib articulating with 

 parapophysis of sixth vertebra; four to eleven additional pairs of ribs posteriorly. 

 Total vertebrae, including six for the Weberian complex and one for the fused 

 preural centra, ranging from 38-58. 



