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, § 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 ii 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 3J times in total length. Snout 
with strongly convex upper profile, shorter than diameter of eye, which is 2.J times 
in length of head, and exceeds a little interocular width ; mouth § width of head, 
sub-inferior, not extending quite to below anterior border of eye ; teeth very small, 
