136 Dr. E. Lonnberg on FisJies from the 



minute teeth. Depth of body 2^ to 2| in total lengtli with- 

 out caudal. Length of head 2| (in younger) to 2| times (in 

 older specimens) in total length. Snout and forehead with 

 straight upper profile, forming a distinct although blunt angle 

 with the outline of the back. Diameter of eye contained 

 1?, (in younger) to \\ times (in older specimens) in length of 

 snout, 3i (in younger) to 4 times (in older) in length of head, 

 1^ to 1 J in interorbital width. Maxillary extending almost 

 to the vertical through the anterior border of the eye. Three 

 series of scales on the cheeks ; opercle with large scales. 

 Dorsal XV (XVI in one specimen) (11-) 12 ; last spine longest, 

 I to ^ length of head ; middle soft rays produced 1^ times as 

 long as longest dorsal spine. Pectoral not extending to origin 

 of anal, pointed, but in all specimens a little shorter than head. 

 Ventral produced, usually reaching vent or a little beyond. 

 Anal III 8, third spine shorter than last dorsal ; soft rays 

 ])roduced 1^ times as long as third anal spine. Caudal 

 truncate or a little emarginate. Scales cycloid, 26-27 ^^ ; 

 lat. line ^^3. Very faint traces of four or five dusky hairs 

 may be seen in some specimens, in others not. A black 

 opercular spot always present, and a blackish spot at the base 

 of the anterior soft rays of the dorsal. Anal often more or 

 less dusky to blackish ; in the latter case, the chin, lower jaw, 

 ventrals, and more or less of the opercle and belly as well as 

 lower half of the caudal are blackish to black. In some speci- 

 mens roundish light spots surrounded by dusky are seen on 

 the posterior part of the soft dorsal and upper half of the 

 caudal. The black-bellied specimens are smaller, but have a 

 larger anal papilla, and an examination of the interior 

 proves that they are males. The larger specimens with 

 light-coloured belly are females. As the genital organs do 

 not contain ripe products, it is evident that the sexual 

 difference in colour is constant, and not confined to the 

 breeding-season. The males measure 10 to 12 cm. in length, 

 the females 12^ to 14 cm. 



I am much indebted to Mr. Boulenger, who has kindly 

 sent me a specimen of Tilapia Zillii (Gervais) from Lake 

 Menzaleh, Egypt, which he regards as most nearly related 

 to the Tilapia from Lake Barombi-ba-kotta. There are, 

 however, several characteristics that show these two fishes 

 to be quite distinct from each other. The shape is different : 

 in T. Zillii the profile forms an even bow without the 

 pronounced nuchal angle of T. kottce ; in the former species 

 the soft rays of the dorsal and anal fins are much more 

 produced, so that they are about twice as long as the 



