158 MK. G. A. BOULENGER ON A COLLECTION 



on hoarl remarkably large. Gill-rakers rather short, 13 on lower part of anterior arch. 

 Dorsal XVI 11 ; last spine longest, half length of head ; longest soft rays produced 

 into filaments, half length of head. Pectoral pointed, | length of head, not reaching 

 origin of anal. Ventral produced into a filament, extending beyond origin of anal. 

 Anal III 9 ; third spine as long as and stronger than last dorsal spine ; some of the 

 soft rays produced into filaments, as in the dorsal. Caudal deeply emarginate. Caudal 

 peduncle IJ as long as deep. Scales very thin, without denticulation, 40 j^^; lat. 1. .^ . 

 Brownish ; dorsal and caudal greyish ; ventrals and anal black, latter edged with white. 



Total length 90 millim. 



A single specimen from the north end of Lake Tanganyika. 



44. TiLAPiA BOOPS. (Plate XIX. fig. 5.) 

 Bouleng. Ann. & Mag. N. H. (7) vii. 1901, p, 5. 



Depth of body equal to length of head, 3^ to 3^ times in total length. Snout with 

 strongly convex upper profile, shorter than diameter of eye, which is 2^ times in length 

 of head, and exceeds a little interocular width ; mouth f width of head, subinferior, 

 not extending qiiite to below anterior border of eye ; teeth very small, tricuspid, in 

 3 rows ; 2 or 3 series of scales on the cheek ; large scales on the opercle. Gill-rakers 

 short, 13 on lower part of anterior arch. Dorsal XII-XIII 14 ; spines slender, equal 

 from the 7th, which measures nearly ^ length of head ; soft rays scarcely longer. 

 Pectoral pointed, as long as head, reaching origin of anal. Ventral produced into a 

 filament, extending beyond origin of anal. Anal III 8-9 ; third spine as long as and 

 stronger than longest dorsal spines. Caudal deeply emarginate, crescentic. Caudal 

 peduncle nearly twice as long as deep. Scales thin, without denticulation, 39-40 j^j^p ; 



lat. 1. i5ii|. Brown above, white beneath ; a blackish opercular spot. 

 Total length 90 millim. 

 Two specimens from Msambu. 



45. TlLAPIA MICKOLEPIS Blgr. 



Kalambo. 



This species grows to a length of 440 millim. Such large specimens lose the 

 secondary cusp of the teeth, and might therefore be referred to the genus Pamtilajna. 



46. Petrocheomis tanganic.^. 



Chromis tanganicce Gunth. Proc. Zool. Soc. 1893, p. 630, fig. 



Kalambo. 



This species grows to a length of 300 millim. Adult specimens agree entirely in 

 their dentition with Petrochromis polyodon Blgr. 



