SYNODONTIS.- 351 



indicate a regime of vegetable substances and small animals, and there is no doubt 

 these fishes show a predilection for decomposing organisms ; they are said to feed 

 chiefly on seeds, but both Mr. Loat and myself have often found fishes of tolerably 

 large size in the stomach, so that they may safely be described as omnivorous. All 

 the species emit sounds, produced by the action of the muscles surrounding the air- 

 bladder, which is compressed by a curious spring-apparatus described by Johannes 

 Miiller *, and by the creaking of the dorsal and pectoral spines. 



The flesh of these fishes is very tasteless and is only eaten by the poor. 



Much information on the morphology of the Synodontis will be found in Vaillant's 

 monograph of 1895-6, quoted above. So many new species have been discovered 

 since its publication, that the systematic part has already become antiquated. 



Synopsis of the Species. 



I. Gill-openings not extending downwards beyond base of pectoral fin. 



A. Movable mandibular teeth not more than half diameter of eye f , 23 or more in number ; 

 maxillary barbel not barbed ; eye supero-lateral. 

 1. Maxillary barbel not or but very feebly margined, the marginal membrane, if distinct, 

 much narrower than the barbel ; humeral process pointed. 



a. Adipose dorsal fin twice and one-third to five times as long as its distance from the 



rayed dorsal. 

 24 to 36 movable mandibular teeth ; interorbital width not half 



length of head ; skin villose on the sides of the body; 



ventral and anal fins obtusely pointed 1. S. scJudl, Bl. Schn. 



33 to 48 movable mandibular teeth ; interorbital width half length 



of head in adult ; skin not villose ; ventral and anal fins 



acutely pointed 2. S. frontosus, Vaill. 



33 to 38 movable mandibular teeth ; interorbital width not quite 



half length of head ; skin not villose ; ventral and anal fins 



rounded 3. S. caudovittatus, Blgr. 



b. Adipose dorsal fin once and one-third to twice and one-third as long as its distance 



from the rayed dorsal. 

 19 to 21 movable mandibular teeth ; skin not villose ; occipito- 



nuchal shield once and one-fourth to once and one-third as 



long as broad 4. S. victories, Blgr. 



45 to 54 movable mandibular teeth ; skin villose on the sides 



of the body ; occipito-nuchal shield once and a half to once 



and two-thirds as long as broad 5. £. afro-fischeri, Hilg. 



* Abh. Ak. Berl. 1843, p. 147, pi. iii. figs. 1-4. 



t The length is that of the exposed part, without the basal part implanted in the lip. 



