2o8 
THE TANGANYIKA PROBLEM. 
the longest dorsals. Caudal with deep crescentic notch. Caudal peduncle twice as 
io 46 — 49 
long as deep. Scales cycloid, 8 °-9° 29 _, 0 ; ,at - 1 ^ _ 42 * 1>ale olive-brown 
above, white below ; faint dark bars across the back and four round dark spots 
on each side, the last at the root of the caudal ; fins yellowish. 
Total length, 115 millim. 
Described from two specimens. Native name, “ Mocupi.” 
As in Tilapia desfontainesi , the dentition of this species may be regarded as 
connecting Tilapia with Paratilapia. 
78. Petrochromis polyodon. — Blgr. 1898. (Fig. p. 197.) 
Crowns of teeth brown. Depth of body 2I to 2j times in total length, length of 
head 2 1 to 3 times. Snout, with convex upper profile, ii to 1 3 diameter of eye, 
which is 4 to 4.} times in length of head and i.4 injnterorbital width ; mouth hardly 
extending to below anterior border of eye ; 4 or 5 series of scales on the cheek ; 
large scales on the opercle. Gill-rakers very short, 12 or 13 on lower part of 
anterior arch. Dorsal XVII. -XVIII. 8-9 ; spines increasing in length to the sixth 
or seventh, which measures about § length of head ; longest soft rays \ to ij length of 
head Pectoral nearly as long as head. Ventral reaching vent or origin of anal. 
