568 Mr. C. T. Regan on the 



II. Dorsal fin small and spineless, or absent ; teeth minute or absent ; 



no post-temporal ; other osteological characters of Schilbe ; ver- 

 tebrae 10-11-1-41-44. (SiluranodontitKe.) 



African Siluranodon, Parailia, Physa- 



ilia. 



III. Dorsal fin absent ; teeth well developed ; post-temporal present ; 

 hypocoracoids not meeting ; air-bladder tubular, transverse, 

 crescentic, curved forward on each side, the horns lying in a pair 

 of recesses open behind, formed by the laminar parapophyses of 

 the fourth and fifth vertebrte, by a ventral lamina which curves 

 upwards anteriorly, and by the lower limb of the supra-clei- 

 thrum; vertebrae 11 -f 41-47. {^Ailiince.) 



Indian Ailia, Ailichthys. 



Family 13. Clariidae. 



Nuked, elongate ; gill-membranes separate, free from 

 isthmus. Dorsal fin spineless, commencing not far behind 

 head; anal long, many-rayed, nearly or quite reaching 

 caudal ; pelvics, when well-developed, 6-rayed ; pectoral 

 with a spine. Head depressed ; mouth transverse, terminal ; 

 bands of villiform or granular teeth in jaws and on vomer ; 

 4 pairs of barbels, nasal, maxillary, and two mandibular. 

 Cranial roof-bones more or less expanded and laminar, the 

 pterotics appearing as a pair of plates at the sides of the 

 supraoccipital ; epiotics concealed beneath supraoccipital ; 

 side of head with two plates, the anterior, " postorbital,'^ 

 attached to the frontal above and behind the orbit, the 

 posterior, " temporal," attached to the pterotic and sapra- 

 cleithrum. Palatine long, rod-like ; pterygoid absent ; 

 mesopterygoid large, connecting the rather small metaptery- 

 goid with vomer (fig. 1, A). Post- temporal absent; supra- 

 cleithrum a plate rigidly attached to pterotic, without lower 

 limb, with a posterior process firmly united to air-bladder 

 capsule ; mesocoracoid present ; hypocoracoids interlocking 

 below. Vertebrae 60 to 107 ; free praecaudals with ribs on 

 well-developed parapophyses ; complex vertebra rigidiy 

 united with fifth, first and skull, by suture and by investing 

 bone ; parapopliyses of fourth and fifth vertebrae forming 

 on each side a transverse cylinder or semi-cylinder with 

 terminal aperture beneath the skin ; air-bladder represented 

 by two sacs enclosed in the cylinders, connected by a 

 transverse tube from which a duct runs to the oesophagus. 



Fresh-water fishes of Africa and Asia. 



The Clariidae are a specialized family, but show relation- 

 ship to the Schilbeidae. A good illustrated description of 

 the head-skeleton of Clarias has been given by Schelaputin 

 (Bull. Soc. Nat.-Moscou, 1905, p. 85). 



