vi INTRODUCTION. 



Gray, Ayres, Day, Sauvage, and Pellagrin. In most cases when no 

 figures had been given, or when the figures were unsatisfactory, original 

 drawings have been prepared by Mr. J. Green and Mr. A. H Searle. 

 Whenever a figure is reproduced from a previous publication, the 

 source has been indicated. The initials A. M. C. refer to the quarto 

 plates of the ' Annales du Musee du Congo,' F. N. to those of the 

 ' Fishes of the Nile.' 



In making use of the descriptions and keys as drawn up in this work, 

 it should be borne in mind that the fins are not included in the total 

 length or greatest depth, whilst in the indication of the total length of 

 the largest specimen examined, which follows the description of every 

 species, the fish is measured from the end of the snout to the extremity 

 of the middle rays of the caudal fin ; by depth of the caudal peduncle, 

 i. e. the free part of the caudal part of the body between the bases 

 of the dorsal or anal and caudal fins, is meant the least depth, whilst 

 the length is that of the muscular part only, the root of the caudal 

 rays being usually covered with scales. By length of the dorsal and 

 anal fins is meant the basal length. The abbreviations used in the fin 

 and scale formula? are too well known to all who work at fishes to need 

 explanation here ; I will only observe that when both Roman and Arabic 

 numerals are used to denote the number of dorsal or anal ravs, the 

 former refer to the simple or to the spinous rays, and the latter to the 

 soft, branched rays, the last of which is usually cleft to the base, and 

 that the interpolation of a comma between the numerals indicates 

 discontinuity in the fins. 



G. A. BOULENGER. 



Zoological Department, 

 25th February, 1909. 



