166 Mr. G. A. Boulenger on the Suborders and 



The parietal bones either separate the frontals from the 

 supraoccipital or are fused with the latter. 



This suborder is divided into six families. The Characinids 

 are the most generalized, and the others are probably derived 

 from them in the manner expressed by the following 

 diagram : — 



LoricariideR. AsprecHnida. 



Cyprinidce. Siluridce. Gymnotidee. 



Characinidce. 



I. Parietal bones distinct from the supraoccipital ; symplectic present ; 



ribs mostly sessile, all or the greater number of the prsecaudal 

 vertebrae without parapophyses. 



Month not protractile, usually toothed ; pharyngeal 

 bones normal ; body scaly ; an adipose dorsal fin 

 often present . . . . 1. Characinidce. 



Mouth not protractile, usually toothed ; pharyngeal 

 bones normal ; body eel-shaped, naked or scaly ; 

 vent under the head or on the throat 2. Gymnotidee. 



Mouth usually more or less protractile, toothless; 

 lower pharyngeal bones large, falciform ; body 

 naked or scaly ; no adipose dorsal fin 3. Cyprinidce. 



II. Parietal bones usually fused with the supraoccipital ; symplectic 



absent ; body naked or with bony scutes ; mouth usually toothed, 

 with barbels ; adipose dorsal fin often present. 



Ribs attached to strong parapophyses ; operculum well 



developed 4. Siluridce. 



Ribs sessile ; parapophyses absent ; operculum more 



or less developed ; mouth inferior 5. Loricariidce. 



Ribs sessile ; strong parapophyses to the vertebrae ; 



operculum absent 6. Aspredinidce. 



Suborder III. Symbranchii. 



Eel-shaped fishes without paired fins, with the pectoral 

 arch free or suspended from the skull and with the anterior 

 vertebrae distinct, without Weberian ossicles. Gill-openings 

 confluent into a single ventral slit. Air-bladder absent. 



