TILAPIA. 



155 



Tilapia mossambica, Bouleng. Tr. Zool. Soc. xv. 1898, p. 4, and Proc. Zool. Soc. 



1899, p. Ill ; Pellegr. Mem. Soc. Zool. France, xvi. 1904, p. 309. 

 Tilapia dumerili, Bouleng. Proc. Zool. Soc. 1899, p. 116 ; Pellegr. t. c. p. 317. 



Depth of body 1\ to 2f times in total length, length of head 2§ to 

 3 times. Head If to 2 times as long as broad, with concave upper 

 profile ; snout rounded, as broad as or a little broader than long, as long 

 as or a little shorter than postocular part of head ; eye 4-j (young) to 

 6| times in length of head, f to § interorbital width, equal to or a little 

 less than praeorbital depth ; mouth large, at least -f width of head, 

 often nearly as wide as head, extending to below anterior border of 



Fig, 101. 



M 



xfr 



V 



'".; 



--3 



"^S^u^;:: 



Tilapia mossambica. 

 Zanzibar Coast, f . 



eye, or not quite so far; teeth in 4 (young) to 8 series*, GO (young) to 

 100 in outer series of upper jaw ; 2 or 3 series of scales on the cheek, 

 width of scaly part at least nearly equal to diameter of eye. Gill-rakers 

 short, 17 to 20 on lower part of anterior arch. Dorsal XV-XVI 10-11 ; 

 last spine longest, f to f length of head ; longest soft ray f to f length 

 of head. Anal HI (rarely IV) 9-10; third spine a little shorter than 

 last dorsal. Pectoral as long as or a little shorter than head, reaching 

 vertical of origin of anal or beyond. Ventral reaching vent or origin of 

 anal. Caudal rounded in the adult, truncate in the young. Caudal 

 peduncle as long as deep or slightly deeper than long. Scales cycloid, 



* In the largest specimen, from Koso Bay, the teeth of the three outer series in both 

 jaws are conical, without a trace of secondary cusp. 



