NANNOCHAEAX. — XENOCHAEAX. s 287 



and root of ventral. Greyish, scales on back edged with darker ; a 

 broad dark lateral band, from the upper part of the gill-cover to the 

 caudal ; a black dot on the upper part of the front of the dorsal. 



Total length 54 millim. 



Casamanza River, Portuguese Guinea. — Type in Paris Museum. 



18. XENOCHARAX. 



Giinth. Ann. & I\Iag. N. H. (3) xx. 18G7, p. 114 ; Boulong. Poiss. Bass. Congo, 

 p. 198 (1901). 



Snout short ; mouth wide, terminal ; teeth very small, bicuspid, in two 

 series in the prsemaxillaries, in three in the lower jaw, in one at the base 

 of the maxillary, which is moderately large. Cheek partly naked ; nostrils 

 close together, separated by a valvular flap ; gill-membranes free from 

 isthmus. Body rather short, strongly compressed. Scales small, strongly 

 ciliated ; lateral line straight, following the middle of the side ; a scaly 

 process at base of ventral fin. Dorsal fin with 20 to 22 rays, above the 

 ventrals ; anal with 14 to 16 rays; a small adipose dorsal fin. 



South Cameroon to Congo. 



Two species : — 



Dorsal originating a little in advance of ventrals . 1. X. sjnhn'us, Gthr., p. 287. 

 Dorsal originating above ventrals 2. X. crassus, Pellegr., p. 288. 



1. XENOCHARAX SPILURUS. 

 Glinth. 1. c. pi. iii. fig. B; Boiileng. op. c. p. 200. 



Depth of body 2J to oj times in total length, length of head 3 to 4 

 times. Head broad and flat above, raised at the occiput ; snout nearly 

 twice as broad as long, as long as or a little shorter than eye, which is 

 lateral and 2f (young) to 4 times in length of head ; interorbital width 

 2 to 3 times in length of head ; maxillary extending to below anterior 

 border of eye. Gill-rakers rather long, slender, 10-13 on lower part of 

 anterior arch. Dorsal 20-22 (4-5 unbranched), originating a little in 

 advance of ventrals, longest rays J to | length of head. Adipose fin 

 scaly at base. Anal 14-16 (4 unbranched). Pectoral f to | length of 

 head. Caudal forked, with long, pointed lobes. Caudal peduncle 

 nearly as long as deep. Scales 68-77 ^^^, 10-12 between lateral line 

 and ventral. Silvery, greenish or blackish olive above ; young with 



