On a new Siluroid Fish from West Africa. 415 



XLIX. — Description of a new Siluroid Fish from West 

 Africa. By G. A. Boulenger, F.R.S. 



Synodontis obesus. 



Praemaxillary teeth in several irregular series, forming a 

 broad band; mandibular teeth 20 to 28, hooked, simple, 

 measuring less than half diameter of eye. Depth of bod y 3 

 to 3-y times in total length, length of head 4 times. Head 

 not or but slightly longer than broad, convex on the occiput; 

 snout obtusely conical, half as long as the head ; eye supero- 

 lateral, its diameter 5 times in length of head, a little more 

 than twice in interorbital width ; upper surface of head 

 strongly granulate or vermiculate from between the eyes; 

 frontal fontanelle narrow. Occipito-nuchal shield obtusely 

 tectiform, longer than broad, granulate or vermiculate like 

 the upper surface of the head, and terminating in two pointed 

 or rounded processes. Gill-cleft not extending below base of 

 pectoral. Maxillary barbel with a broad membranous fringe, 

 longer than the head, not reaching much beyond middle of 

 pectoral spine ; mandibular barbels inserted on a straight 

 transverse line, outer shorter than the head, more than twice 

 as long as inner. Lips much developed. Humeral process 

 granulate, acutely pointed, extending as far as occipito-nuchal 

 shield. Dorsal II 6 ; spine strong, as long as the head, 

 striated, with one or two very feeble seme in front near its 

 extremity, and about 10 feeble seme behind in its upper 

 half. Adipose fin 4 times as long as deep, as long as or a 

 little shorter than the head, \\ to '1\ as long as its distance 

 from the dorsal. Anal IV 7-8. Pectoral spine nearly as 

 long as dorsal, striated, feebly serrated on the outer edge, 

 with 14 to 16 strong serrae on the inner edge. Ventral 

 reaching or nearly reaching anal. Caudal deeply bifurcate. 

 Skin of body smooth. Brown above and beneath, spotted 

 and dotted with darker. 



Total length 220 millim. 



This species is founded on three specimens, two from the 

 Gaboon, and a larger one which, collected by Miss Kingsley 

 in the Opobo River, Old Calabar, has been referred by 

 Giinther to S. serratus, Riipp. (Ann. & Mag. Nat. Hist. ((]) 

 xvii. 1896, p. 277). S. serratus differs in the more numerous 

 mandibular teeth, the more elongate body, the stronger ante- 

 rior serrature of the dorsal and pectoral spines, the longer 

 occipito-nuchal shield, the longer adipose fin, and the absence 

 of spots. S. obesus stands much nearer to S. gamhiensis 

 Gthr.j which differs in the thicker barbels, the maxillaries 

 lacking every trace of a fringe. 



