SILURID.E. 219 



B. Dorsal fin divided into two, the posterior portion adipose. 



Sides of head protected by bony shields ; adi- 

 pose dorsal fin large and supported by 

 bony rays (the produced neural spines) . 6. Heterobranchus, Geoffr., p. 272. 



Sides of head naked, only the postorbital shield 



being present ; adipose dorsal fin small . 7. Diaotopterus, Blgr., p. 276. 



II. Plotosin^e. — A short dorsal fin in front, with a pungent spine ; a second 



dorsal and a long anal, united with the caudal ; gill-membranes free from 

 isthmus ; air-bladder moderately large, free. 



8. Plotosus, Lacep., p. 278. 



III. Silurin.e. — Dorsal fin very short or absent; adipose dorsal fin very small ; 

 anal fin much elongate ; gill-membranes free from isthmus. 



A. Dorsal fin with a spine. 



Adipose fin present 9. Eutropius, M. & T., p. 279. 



Adipose fin absent 10. Schilbe, Cuv., p. 293. 



B. Dorsal fin without spine ; adipose fin present. 



Teeth absent 11. Silvranodon, Blkr., p. 29.S. 



0. No rayed dorsal fin. 



Adipose fin present 12. Physailia, Blgr., p. 300. 



Adipose fin absent 13. Parailia, Blgr., p. 302. 



IV. Bagrin^e. — Dorsal fin short; adipose fin present, or transformed into a 

 second rayed fin ; anal fin short ; gill-meinbranes free or very narrowly 

 attached to isthmus. 



A. Gill-membranes more or less notched in the middle ; nostrils widely 

 separated from each other. 

 1. Nasal barbel present *. 



a. Teeth on the palate. 



Dorsal fin with 8-11 branched rays; adipose 



fin very large 14. Bagrus, Cuv., p. 304. 



Dorsal fin with 5-6 branched rays ; adipose 



fin moderate or small 15. Chrysiehtliys, Blkr., p. 314. 



Dorsal fin with 6 branched rays ; second dorsal 



fin rayed, with an anterior spine in the 



adult 16. Clarotes, Kner, p. 341. 



b. Palate toothless. 



Dorsal with 6-7 branched rays 17. Gephjroglanls, Blgr., p. 344. 



2. Nasal barbel absent. 



a. Anterior nostril on upper surface of snout; dorsal with 5-7 branched 

 rays. 



* Sometimes very minute in Oephyroglanis. 



