Chi/tsijication of thu Order O.^turiojihysi. 571 



II. Ilrtiljels simple ; ninxillaries behind the prneniaxillaries ; parapo- 

 pliyses of sixth vt'itebni very strong; head depressed; mouth 

 vith a papillose circular lip. 



ChiloylanU, Euchilichthys, Atopuchilus. 



Tlie Synodoiitiilie resemble tlic Soiitli American DoracUdre 

 to a ecrtuiu extent in their rcstrietecl gill-openings, nuclial 

 shieltl, and elastic spring apparatus. But iu the Doradidie 

 the epioties are prominent cranial roof-bones whicii join the 

 nuchiil plates (tig. 3, A), a mesopterygoid is present but a 

 niesocoracoid absent, the fourth par;ip()|)hysis is not divided 

 into anterior and posterior rami and its distal plate is attaclied 

 to tlie lateral instead of the anterior wall of the air-bladder, 

 and the tifili parapophysis is vestigial or absent. 



Family 16. Malopternridae. 



The African Mulopternrus electricns (lifters from the 

 Bagrida^ in the absence of the dorsal fin. the restricted gill- 

 openings, and the development of a subcutaneous electric 

 organ extending over the whole body. Osteological characters 

 indicate relationship to the Bagridffi, but there are several 

 features of specialization. Pterygoid and mesopteiygoid are 

 absent, the metapterygoid is firmly connected with a hori- 

 zontal ledge formed by the lateral ethmoid and orhito- 

 sphenoid, and the quadrate extends forward external to the 

 metapterygoid to meet the extremity of the recurved 

 prfcmaxillary. The skull is narrowed and compressed 

 l)etween the orbits and strongly expanded and depressed 

 behind them, and the sphenotic sends out a strong lateral 

 process to above the eye. The pectoral arch is rather 

 loosely attached, the upper limb of the supracleithrnni 

 articulating in a socket between the post-temporal and the 

 epio.tic, the lower limb connected to the b.isioccipital by 

 ligament. The vertebrae number 41 to 44 (20-2.2 + 21-22) ; 

 the anterior ramus of the parapophysis of the fourth 

 vertebra is free from the supra cleithrum, thin proximally 

 and expanded distally into a transverse vertical plate, in- 

 serted in the anterior wall of the air-bladder. The air- 

 bladder has a large posterior sac, connected by a tube with 

 the smaller anteiior division, which represents a normal 

 bladder. 



Family 17. Pimelodidae. 



Gill-membranes separate, free from isthmus. Dorsal fin 

 typically anterior and with a spine (above or behind the 

 pelvics and without a spine in Heptapterus and Nannoglanis) ; 

 adipose fin present; anal short or of moderate length; 



38 >^ 



