SILUEID^. 81 



•*. Caudal fia not forked, rounded or usually somewhat emarginate, nearly truncate 

 when spread open : 

 J. Body moderately elongate, depth one-fifth or more of length ; branchiostegals 

 normally 9 or 10 : 

 c Anal fia very long, its base one-fourth or more of length of body, of 24 to 26 

 rays; dorsal spine normally nearer snout than adipose fin : 

 — . Head and body elongated ; the dorsal region considerably elevated ; the 

 head quite long and narrowed forwards; much longer than 

 broad ; its width in front of eye only about half its length ; 

 mouth rather narrow, with equal jaws; barbels long; adipose 

 fin large ; spines strong ; dorsal fin very high ; anal fin long 



and deep; caudal fin short; color dark Erebennus, 11. 



Head wide and fl^attish, not much longer than broad ; rounded in front ; 



the mouth very wide ; the dorsal region not much elevated; 

 body more or less stout and thick ; branchiostegals 8 or 9 , 



jaws equal or upper jaw longest Natalis, 12. 



w. Dorsal considerably nearer snout than adipose fin : 

 X. Jaws equal ; spines very short ; anal rays 25; colors yellowish-brown, Lividus, b. 

 XX. Upper jaw distinctly longest : 

 y. Anal rays 24 or 25, its rays less than half head, its base 3^ in length of 

 body ; the nape not swollen : 



z. Colors pale; yellowish-brown Cupreus,c. 



zz. Colors dark ; black or greenish Ccenosus, d. 



yy. Anal rays 26; base of anal 3| in length, its rays short, less than half length 

 of head ; spines weak ; head 3J to 3f in length ; distance to 

 dorsal spine 2^ to 2| ; the nape more or less swollen and 



elevated Anto7iiensis, e. 



yyy. Anal rays 27, its base elongate, 3^ in length, its longest rays more than 

 half head ; spines strong ; head short, 4 in length, the distance 



to dorsal nearly 3; nape not swollen Analis,f. 



WW. Dorsal rather nearer adipose fin than snout ; the posterior part of the body 

 being much thicker and proportionally shortened ; the caudal 

 fin short; dorsal and. ventral outlines nearly parallel; jaws 



about equal Natalis, a. 



cc. Anal fin moderate, of 19 to 22 rays; branchiostegals normally 8 or 9 : 

 d. Lower jaw distinctly longest; anal rays 20 : 



e. Body moderately elongate, depth 4^ to 5 in length; head 3^ to 4 ; barbel 

 long; mouth wide; head longer than broad, rather narrowed 

 forward; profile rather steep, pretty evenly convex; dorsal re- 

 gion more or less elevated ; dorsal spine nearer snout than adi- 

 pose fin ; lower jaw strongly projecting ; color blackish (varying 

 in subspecies ti'Zz(r«s to head blunter and flatter above; dorsal 



spine rather nearer adipose fin) Vulgaris, 13. 



dd. Jaws equal, or upper jaw projecting beyond lower : 

 /. Eyes distinct, well developed : 



g. Head moderately broad, a nearly even slope from the tip of the snout to 

 the elevated base of the dorsal : 

 — .Body sharply mottled with brown, greenish, and whitish; the colora- 

 tion therefore singular among Catfishes ; jaws equal or nearly so ; 

 depth about 4 in length ; slope of profile very steep ; dorsal fin 

 high ; the spine more than half length of head ; dorsal spine 

 nearer adipose fin than snout ; barbels long ; branchiostegals 

 10; head 3^ in length Marmoratus, 14. 



Bull. N. M. Ko. 10— G 



