Order LABYRINTHICI. 



Physoclistic. Cylindrical and elongate or compressed and 

 oblong. Mouth large or small. Intermaxillaries protractile, exclud- 

 ing the edentulous maxillaries from the oral border. The jaws 

 with fixed, conical teeth; in one case (Helostoma] only movable 

 ones on lips. Vomer and palatines with or without teeth. Teeth 

 on parasphenoid present. Scales large or moderate, cycloid or 

 ctenoid. Lateral line present and continuous, or interrupted, 

 or vestigial, or absent. The single dorsal fin long, inserted above 

 base of pectorals, longer than anal fin, or shorter than it and 

 beginning behind base of pectorals. Dorsal and anal with or 

 without spines, the rays branched or not. Pectorals situated 

 below middle of height. Ventrals thoracic, subabdominal or 

 absent, composed of six rays, the outer of which is unbranched 

 or spine-like; the rays may be reduced to one. Pelvic bones 

 remote from cleithra or attached to them. Parietal bones are 

 separated by the supraoccipital, an orbitosphenoid wanting. 

 Four gills. Pseudobranchiae none or rudimentary. A supra- 

 branchial organ constituted by a system of labyrinthic lamellar 

 processes from the outside of the epibranchial of the first 

 branchial arch, enclosed in an accessory cavity, separate from 

 'the pharyngeal cavity, but in communication with the branchial 

 cavity, by an opening above the two anterior gillslits. In 

 Ophiocephalidae the suprabranchial cavity is more like a diver- 

 ticulum of the pharyngeal cavity, as it is in open communi- 

 cation with it. It is also without a labyrinthiform organ but 

 covered by a mucous membran fit for accessory respiration. 



Synopsis of the suborders of Labyrinthic i. 



1. Dorsal and anal with articulated rays only. Ventrals, 

 when present, with six rays. Scales cycloid. Supra- 

 branchial cavity without labyrinthiform organ Ophiocephaloidei p. 313. 



2. Dorsal and anal with one or more spines. Ventrals with 

 five or less rays and a spine, or reduced to a single 

 ray. Scales ctenoid. Suprabranchial cavity with a laby- 

 rinthiform organ Anabantoidei p. 330. 



