204 



THE TANGANYIKA PROBLEM. 



74. Tilapia trematocephala. — Blgr. 1901. (Fig. p. 195. Upper.) 



Depth of body equal to length of head, 3^ times in total length. Snout, with 

 slightly convex upper profile, a little shorter than diameter of eye, which is contained 

 3 times in length of head and exceeds interocular width ; mouth small, its width 

 half that of head, extending to between nostril and eye ; teeth very small, in 2 rows, 

 outer bicuspid ; 3 series of scales on the cheek ; large scales on the opercle ; 

 orifices of sensory canals on head remarkably large. Gill-rakers rather short, 13 on 

 lower part of anterior arch. Dorsal XVI. 1 1 ; last spine longest, half length of 

 head ; longest soft rays produced into filaments, half length of head. Pectoral 

 pointed, J length of head, not reaching origin of anal. Ventral produced into 

 a filament, extending beyond origin of anal. Anal III. 9 ; third spine as long as 



Telmatochromis temporalis. See p. 194. 



and stronger than last dorsal spine ; some of the soft rays produced into filaments 



as in the dorsal. Caudal deeply emarginate. Caudal peduncle \h as long as deep. 



3 28 



Scales very thin, without denticulation, 40 — ; lat. 1. — - — . Brownish, dorsal 



10 ? 



and caudal greyish ; ventrals and anal black, latter edged with white. 



Total length, 90 millim. 



Described from a single specimen from the north end of Lake Tanganyika. 



75. Tilapia boops. — Blgr. 1901. (Fig. 3, p. 175.) 



Depth of body equal to length of head, 3J to 3$ times in total length. Snout 

 with strongly convex upper profile, shorter than diameter of eye, which is 2h times 

 in length of head, and exceeds a little interocular width ; mouth f width of head, 

 sub-inferior, not extending quite to below anterior border of eye ; teeth very small, 



