202 
THE TANGANYIKA PROBLEM. 
72. Tilapia labiata. — Blgr. 1898. (Fig. p. 173.) 
Outer teeth rather large, feebly notched ; inner teeth very small, tricuspid, 
in 3 or 4 series. Depth of body equal to length of head, 2$ to 2] times in 
total length. Snout, with straight upper profile, 1] to 1] diameter of eye, which is 
3} to 4} times in length of head and equals interorbital width ; maxillary not 
extending to below anterior border of eye ; 3 or 4 series of scales on the 
cheek ; large scales on the opercle ; lips very strongly developed, both produced 
into a large triangular lobe in front. Gill-rakers moderate, 15 on lower part 
of anterior arch. Dorsal XVIII. 10; middle dorsal spines longest, about J length 
of head, and a little shorter than longest soft rays. Pectoral | to \ length of head. 
Ventral reaching origin of anal. Anal III. 6-7 ; third spine longest, as long as 
longest dorsal, slightly shorter than longest soft rays. Caudal truncate. Caudal 
peduncle slightly longer than deep. Scales finely denticulate on the border, 
33-35 
5—6 
22 — 25 
lat. 1. — — — . Pale olive, with 10 more or less distinct darker 
12—13' 13 — 15 
cross-bars ; fins of greyish brown ; dorsal sometimes with oblique dark and light 
streaks ; caudal with numerous round dark spots between the rays. 
Total length, 170 millim. 
Described from four specimens from Kinyamkolo. 
This species is easily recognisable by the extraordinary development of the lips, 
which bears a curious resemblance to that observed in the Central American Heros 
labiatus. It appears to be nearest allied to Ctcnochromis nuchisquamulatus , 
Hilg. , and C. Sauvagii , Pfeffer, from the Victoria Nyanza. 
73. Tilapia pleurotania. — Blgr. 1901. (Fig. p. 200.) 
Depth of body 2} to 3 times in total length, length of head 3 to 3-1 times. Snout, 
with profile descending in a straight line, as long as the diameter of the eye, which 
is contained 3i to 3^ times in length of head, and exceeds a little interocular width ; 
mouth small, its width half or a little more than half that of head, extending to below 
nostril, or between nostril and eye ; teeth very small, in 3 series, outer bicuspid ; 
3 or 4 series of scales on cheek. Gill-rakers short, 10 to 12 on lower part of 
anterior arch. Dorsal XV. -XVII. 11-12; last spine longest, a little less than 
half length of head ; longest soft rays § length of head. Pectoral pointed, a little 
shorter than the head, not quite reaching oiigin of anal. Anal III. 8-10; third 
spine a little shorter than last dorsal spine. Caudal deeply notched and crescentic. 
Caudal peduncle ii as long as deep. Scales very thin, without denticulation, 
4 22 — 24 
32-35 ; lat. 1. . Pale brown above, white beneath ; a blackish 
lateral stripe, from the opercle to the caudal ; fins greyish ; small, round, white spots 
on soft dorsal and caudal. 
Total length, no millim. 
Described from several specimens from the north end of Lake Tanganyika, and 
from the mouth of the Rusisi River. 
