CJassiJtcation of the Order O.itariophysi. 571 



II. Barbels simple ; maxillaries behind the prsemaxillaries ; parapo- 

 pli yses of sixth vertebra very strong- ; head depressed ; mouth, 

 with a papillose circular lip. i ■ 



Chiluglcmis, Euchilichthys, AtopochUus. ''- 



The Synodontidse resemble the South American Doradidpe 



to a certain extent in their restricted gill-openings, nuchal 



shiehl, and elastic spring apparatus. But in the Doradidae 



the epiotics are prominent cranial roof-bones which join the 



nuchal plates (Hg. 3, A), a mesopterygoid is present but a 



mesocoracoid absent, the fourth parapophysis is not divided. 



into anterior and posterior rami and its distal plate is attached 



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



and the fifth parapophysis is vestigial or absent. 



/ 

 Family 16. Malopteruridae. 



The African Malopterurus electricus differs from the 

 BagridiK 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 Bagridsej but there are several 

 features of specialization. Pterygoid and mesopterygoid are 

 absent, the metapterygoid is firmly connected with a hori- 

 zontal ledge formed by the lateral ethmoid and orbito- 

 sphenoid, and the quadrate extends forward external to the 

 metapterygoid to meet the extremity of the recurved 

 praemaxillary. The skull is narrowed and compressed 

 between 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 supracleithrnm 

 articulating in a socket between the post-temporal and the 

 epiotic, the lower limb connected to the b.isioccipital by 

 ligament. The vertebrae number 41 to 44 (20-22 + 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 aii*-bladder. The air- 

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

 the smaller auteiior division, which represents a normal 

 bladder. 



Family 17. Pimelodidse. ^ 



Gill-membranes separate, free from isthmus. Dorsal fin 

 typically anterior and with a spine (above or behind tiie 

 pelvics and without a spine in Heptapterus and Nannoglanis) ; 

 adipose fin present ; anal short or of moderate length ; 



38>* 



