6 SILURID.K. 



b. Gill-cavity without accessor// sac. 



a a. The eye is situated above the level of the angle of the mouth. 



a. Caudal fn rounded. 

 Adipose fin none 8. Silukus, p. 32. 



j3. Caudal fin o/iliquely emarginate. 

 Adipose fin none 9. Silurichtiiys, p. 35. 



y. Caudal fin forked. 



Adipose fin none ; teeth villiform 10. Wallago, p. 36. 



Adipose fin none ; teeth long, widely set ... 11. Belodontichthys, p. 37. 

 Adipose fin present 12. Eutropiichthys, p. 38. 



bb. The eye is situated behind, and partly even below the level of, the angle 

 of the mouth. 



a. The mandibulary barbels are placed at some distance behind the sym- 

 physis ; or if they are absent, the posterior nostrils are neither wide, 

 nor placed more closely together than the anterior. 



* Mandibles without enlarged muciferous cavities. 



No adipose fin ; dorsal quite rudimentary or entirely absent. 



13. Cryptopteeus, p. 38. 



No adipose fin ; dorsal fin with several rays, but without pungent spine. 



14. Calliciirous, p. 45. 



No adipose ihi ; dorsal fin with a pungent spine. 



15. ScniLBE, p. 49. 



Adipose fin present ; dorsal with a pungent spinje. . 



16. EuTROPius, p. 52. 



** Mandibles with the muciferous cavities enlarged. 

 No adipose fin 17. He.misilurus, p. 54. 



/3. The mandibulary barbels, if present, are placed immediately behind the 

 symphysis ; the nostrils are more or less wide, and the anterior are 

 always open, placed quite in front of the snout, and getierally more 

 remote from each other than the posterior. 



* Four maiulihnldri/ barbels placed in a straight line immediately 

 behind the sz/m/J/i/s/s of the lower Jaw ; nostrils rather wide, espe- 

 cially the lii}nhr ones, which are close together on the top of the 

 snout. 



Adipose On none ; dorsal fin without pungent spine. 



18. SiLURANODON, p. 55. 



Adipose fin present ; no other dorsal 19. Ailia, p. 55. 



Adipose fin none ; dorsal fin with a pungent spine. 



20. SCIIILBICHTHYS, p. 56. 



Adipose fin present ; dorsal fin with a pungent spine ; nasal barbels none. 



21. Lais, p. 57. 



Adipose fin present ; dorsal fin with a pungent spine ; a pair of nasal barbels. 



22. Pseudeutropius, p. 58. 



** Two mandibidary barbels, placed immediately behind the symphysis 

 of the lower jaw ; nostrils rather wide, the anterior being quite in 

 front of the snout. 



Palatine teeth separate from tho.se of the vomer. 



23. Pangasius, p. 61. 



