1. Eleven species are redescribed on the basis of new material.
2. In addition, three new species (Haplochromis theliodon; H. empodisma and H. saxicola) are described.
3. Several phyletic lines are represented amongst these fourteen species, which include H. cinereus, a species once thought to represent one of the basic types from which the present-day species-flock had evolved. Evidence now available suggests that, anatomically, H. cinereus is not sufficiently generalized to retain this distinction.
4. Notes are given on the feeding habits and bionomics of the species.
5. Three species (H. obtusidens, H. pharyngomylus and H. ishmaeli) are largely or entirely mollusc-eaters ; three others (H. humilior, H. theliodon and H. riponianus) feed on both insects and molluscs ; one, H. martini, .is a piscivorous predator and seven others are insectivore/omnivores.
6. One species, H. niloticus (nom. nov. for Tilapia bayoni Blgr. 1911) is known only from the Victoria Nile, whilst H. ishmaeli occurs in both Lakes Victoria and Edward ; H. humilior is found in Lake Victoria and the Victoria Nile.
7. The assumed distribution of H. macrops in both Lakes Victoria and Edward is discussed ; no definite conclusion can be drawn from the material now available.
8. Two groups of specimens are dealt with in separate appendices because of their uncertain taxonomic position. One group is apparently allied to or even conspecific with H. pharyngomylus and the other with H. ishmaeli. No conclusion can be reached on the status of these aberrant fishes.