520 CICHLID^E. 



Chromis niloticus, part., Gervais, Zool. Pal. Gen. p. 205, pi. xlv. fig. 3 (1869), and Journ. de Zool. 



iii. 1874, p. 455. 

 Chromis mossambicus, part., Steindacriner, Sitzb. Ak. Wien, lx. i. 1870, p. 23. 

 Chromis zillii, Sanvage, Bull. Soc. Philom. (7) i. 1877, p. 163; Holland, Rev. Scientif. (4) ii. 1894, 



p. 418, fig. 

 Chromis menzalensis, Mitchell, Eep. Fish. L. Menzaleh, p. 13, pi. iii. (1895). 

 Chromis tristrami, Giinther, Proc. Zool. Soc. 1896, p. 218. 

 Tilapia tristrami, Boulenger, Tr. Zool. Soc. xv. 1898, p. 6. 

 Tilapia menzalensis, Boulenger, Proc. Zool. Soc. 1899, p. 119. 

 Tilapia zillii, Boulenger, 1. c. ; Pellegrin, Mem. Soc. Zool. France, xvi. 1904, p. 327. 



Depth of body twice and one-sixth to twice and two-thirds in the total length, 

 length of head twice and two-thirds to three and one-third times. Snout with straight 

 or slightly concave profile, once (young) to twice the diameter of the eye, which is 

 contained three and a half (young) to five times in the length of the head and once 

 (young) to twice in the interorbital width ; width of the praeorbital greater than the 

 diameter of the eye in the adult ; mouth rather large, three-fifths to four-fifths the width 

 of the head, with thick lips; maxillary extending to between the nostril and the eye or 

 to below the anterior border of the latter ; teeth in three to six series in each jaw, outer 

 largest, 20 (young) to 60 in the upper jaw, and separated from the others by a very 

 distinct interspace ; three or four series of scales on the cheek, the depth of the scaly 

 part below the eye equal to the diameter of the eye in the young, much greater in the 

 adult ; large scales on the opercle. Gill-rakers short, 8 to 10 on lower part of anterior 

 arch. Dorsal fin with 14 to 16 spines and 10 to 13 (usually 12) soft rays; spines 

 increasing in length to the last, which measures two-fifths to three-fifths the length of 

 the head; median soft rays more or less produced in the adult. Anal fin with 3 

 spines and 7 to 10 (usually 9) soft rays ; third spine usually shorter than the longest 

 dorsal. Pectoral fin pointed, as long as the head or a little shorter, rarely extending 

 as far as the vertical of the origin of the ventral fin. Ventral fin usually reaching the 

 vent or the anal fin. Caudal fin truncate, rounded in old specimens. Caudal peduncle 

 as long as deep or a little deeper than long. Scales not or but very feebly denticulate, 

 30-33 j^f 5 ; lateral lines j^jg. 



Olive or brown in spirit, usually with six to eight more or less distinct dark cross- 

 bars, with or without a dark stripe along the middle of the side ; a black opercular 

 spot; sometimes a dark vertical bar below the eye; vertical fins with dark markings, 

 which often form oblique streaks on the dorsal and anal ; a black spot on the base of 

 the anterior soft dorsal rays ; caudal fin often dark, with round whitish spots. But 

 this species varies very much in colour and markings. According to Mr. Loat's notes 

 and sketches, the dark transverse bands are usually of a blackish green, the light inter- 

 spaces between them being shot with green, blue, or pink ; the lower parts are often 

 of a dark blood-red, which colour may extend to behind the gill-opening. Patches of 



