392 SILUKIM. 



B. Movable mandibular teeth not more than 65 ; band of periaxillary teeth 

 not extending along the whole width o£ the mouth ; head more or less 



rugose above. 



1. Humeral process pointed, bearing spines; movable mandibular teeth 36 



to 55 ; skin villose on the sides. 

 Snout longer than postocular part of head ; 



maxillary barbel not distinctly fringed ; 



ventral not reaching beyond origin of anal. 3. S. acanthomias, Blgr., p. 400. 

 Snout not longer than postocular part of head ; 



maxillary barbel not distinctly fringed ; 



ventral reaching beyond origin of anal . 4. S. ornias, Gthr., p. 401. 

 Snout not longer than postocular part of head ; 



maxillary barbel broadly fringed ; ventral 



reaching anal 5. S. budyetti, Blgr., p. 403. 



2. Humeral process pointed, without spines. 



a. Spine of dorsal fin not serrated in front*. 



a. Maxillary barbel f to If times length of head. 



* Snout not or but little longer than postocular part of head, 

 t Maxillary barbel not or but feebly fringed. 



\ Movable mandibular teeth 20 to 48 ; base of adipose dorsal 

 2J to 6 times its distance from rayed dorsal. 

 § Interorbital width not half length of head ; 24-36 movable 

 mandibular teeth ; humeral process longer than broad. 

 Inner mandibular barbel with the basal branches 

 short, with tubercular ramifications ; pec- 

 toral spine feebly serrated on outer border ; 

 ventral usually not reaching anal ; skin 



more or less villose on sides 6. S. scliall, Bl. Schn., p. 404. 



Inner mandibular barbel with the basal branches 

 short, with tubercular ramifications ; pec- 

 toral spine moderately or strongly serrated 

 on outer border ; ventral usually reaching 



anal ; skin smooth 7. S. gambiensis, Gthr., p. 407. 



Inner mandibular barbel with long slender 

 branches without tubercular ramifications ; 

 pectoral spine moderately serrated on 

 outer border; skin smooth 8. S. ocellifer, Blgr., p. 409. 



§ § Interorbital width half, or nearly half, length of head in 

 adult ; 33-48 movable mandibular teeth. 

 Ventral reaching anal, both acutely pointed ; 

 humeral process not much longer than 

 deep; skin smooth 0. S. frontosus, Vaill., p. 410. 



* Sometimes very slightly in S. caudovittatus and S. gambianiis. 



