TILAPIA. 157 



a little shorter than postocular part of head, slightly broader than long, 

 1| to 1| diameters of eye, which is 4 to 5 times in length of head and 

 1 J to nearly twice in interorbital width ; mouth large, extending to 

 below anterior border of eye or a little beyond ; teeth very small, in 

 3 or 4 series, about 60 in outer series of upper jaw ; 2 or 3 series of scales 

 on the cheek. Gill-rakers short, 17 on lower part of anterior arch. 

 Dorsal XV-XVI 12-13 ; last spine about A length of head ; middle soft 

 rays much produced, as long as head. Anal III 10 ; third spine a little 

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

 beyond origin of anal. Ventral extending beyond origin of anal. 

 Caudal truncate. Caudal peduncle as long as deep. Scales cycloid, 

 28-31 jj ; lateral lines r^rr^ ^ ai 'k olive-brown ; a rather indistinct 

 dark opercular spot ; vertical fins and vcntrals blackish. 



Total length 149 millim. 



German East Africa and Mozambique. — Type, in Hamburg Museum, 

 examined. 



7. TILAPIA NATALENSIS. 



Chromis niloticus, part., Peters, Arch. f. Nat. 1855, p. 267, and Reise Mossamb. 



iv. p. 23 (1868) ; Pfeff. Jahrb. Hamb. Wiss. Anst. x. 1893, p. 149, pi. iii. 



figs. 1-4, and Thierw. O.-Afr., Fische, p. 10, fig. (1896). 

 Chromis mossamlicus, part., Griintb. Cat. Fish. iv. p. 268 (1862). 

 Chromis natalensis, M. Web. Zool. Jahrb., Syst. x. 1897, p. 147. 

 Tilapia natalensis, Bouleng. Proc. Zool. Soc. 1899, p. 113, and Poiss. Bass. Congo, 



p. 457 (1901) ; Pellegr. Mem. Soc. Zool. France, xvi. 1904, p. 311. 



Depth of body 1\ to 2§ times in total length, length of head 2f to 3^ 

 times. Head If to 2 times as long as broad; snout rounded, with 

 straight or convex upper profile, as broad as or a little broader than 

 long, f to f postocular part of head ; eye 3 (young) to 5| times in length 

 of head, 1 (young) to 2 times in interorbital width, equal to or a little 

 less than pneorbital depth ; mouth moderate, f to f width of head, 

 extending to between nostril and eye ; teeth in 3 (young) to 6 series *, 

 50 (young) to 140 in outer series of upper jaw; 2 or 3 series of scales 

 on the cheek, width of scaly part not greater than diameter of eye. 

 Gill-rakers short, 15 to 20 on lower part of anterior arch. Dorsal 

 XV-XVI (rarely XVII or XVIII) 10-12 ; last spine longest, f to a 

 little over \ length of head ; longest soft rays § to f length of head. 



* In a large specimen, from Umfulosi, a number of the outer upper teeth are simply 

 conical. 



