TILAPIA.— PETEOCIIKOMIS. 267 



"\ entral more or less produced, reaching origin of anal or beyond. 

 Caudal with deep crescentic notch. Caudal peduncle a little longer 

 than deep. Scales finely denticulate, 55-65 ~^; lateral lines g^?- 

 Dark olive-brown above, shading to lighter, with some yellow, below ; 

 a series of about five irregular blackish blotches on the side of the 

 body ; dorsal with yellow spots, sometimes tipped with black. 



Total length 115 millim. 



Lake Tanganyika. — Type in Congo Museum, Tervueren. 



1- A.J- Sumbu. Dr. ^Y. A Cumiington (C). 



2-3. Ad. Niamkolo. 



4. Skel. 



5. Ad. Moliro. Dr. L. Stappers (C.j. 



2. PETROCHROMIS. 



Bouleng. Tr. Zool. Soc. xv. 18'J8, p. 20, and Poiss. BaPs. Coiio;o, p. 479 (1901) ; 

 Pellegr. Mem. Soc. Zool. France, xvi. 1904, p. 350 ; Bonleng. Fisli. Nile, 

 p. 535 (1907). 



Barely separable from Tilapia, diff'ering only in the broader bands of 

 teeth in the jaws, showing when the mouth is closed, the teeth being 

 all very slender with expanded tricuspid crowns bent inwards and 

 disposed very irregularly *. Yertebrte 31-32 f. 



Great Lakes of Africa. 



Syno])sis of the Species. 



\. 3 series of scales on tlie clieek ; 20-28 gill-rakers on lower part of anterior 

 arch. 

 D. XVI-XVII 11-13; A. Ill 9-10; Sc. 32- 

 33 J7^; dorsal spines equal from the sixth 



or eighth I. P. tanganwe, Gthr., p. 2G8. 



D. XVI-XVII 13; A. Ill 9-10 ; Sc. 32-34 j^; 



dorsal spines increasing in length to the 



],,c,j- 2. P. andersonii, Blgr., p. 2G9. 



* As in Tilajna, the teeth are much more numerous and form broader bands in the 

 adult than in the young. Thus, in P. tancjanicce the transverse series vary with age from 

 5 to 12, the outer series containing 58-100 teeth. 



t 31 (17-)-14) in P. iant/anicce, .'il-' (17 + 15) in P pohjodon. 



