. Bulletin of the British Museum (Natural History). 12 E. TREWAVAS Dentition. In the 68 mm specimen all the teeth are uniciispid with no shoulder. In the 68 and 71 mm specimens there is only one, irregular inner row, of few, very small teeth; in the 71 mm fish I cannot find any inner teeth in the upper jaw. At SL 150 mm there are 1-2 irregular rows of inner teeth in the upper jaw, 2 in the lower. In all the outer teeth are conical, firm, the two or three anterior on each side in the lower jaw spaced and thicker than the rest. In the 150 mm fish the tooth-band of the lower jaw is broadened ante
. Bulletin of the British Museum (Natural History). 12 E. TREWAVAS Dentition. In the 68 mm specimen all the teeth are uniciispid with no shoulder. In the 68 and 71 mm specimens there is only one, irregular inner row, of few, very small teeth; in the 71 mm fish I cannot find any inner teeth in the upper jaw. At SL 150 mm there are 1-2 irregular rows of inner teeth in the upper jaw, 2 in the lower. In all the outer teeth are conical, firm, the two or three anterior on each side in the lower jaw spaced and thicker than the rest. In the 150 mm fish the tooth-band of the lower jaw is broadened anteriorly by wider spacing between the rows (fig. 8). There is no evidence of a pluricuspid stage. Both this species and Pelmatochromis nigrofasciatus have a characteristically pigmented tooth-bed in which each inner tooth pierces a tiny pigment-free disc. The pharyngeal teeth are narrow but rather coarse, the posterior bicuspid, the anterior conical, (fig. 7).. I mm Fig. 8. Pterochromis congicus, SL 150 mm, plan of dentition of lower jaw and isolated outer and inner teeth to the same scale. Key to the Species of PELMATOCHROMIS la Outer teeth unicuspid in adult, shouldered in juveniles, some notched in very young; inner much smaller than outer, some retaining minor cusps in adult, others replaced by unicuspids; premaxillary pedicels 21-^-2tj% length of head; gill- rakers 8-14 on lower part of first arch; a tilapia mark. Congo nigrofasciatus lb Teeth unicuspid, curved cones at all known stages, inner shaped as outer and only a little smaller; premaxillary pedicels 27-7-33o''i, length of head; gill-rakers 6-8 on lower part of first arch .......... 2. 2a A tilapia-mark; lower jaw 35-38% length of head; 2 or 3 epibranchial gill-rakers. Congo ocellifer 2b No tilapia-mark in adult, but a black spot on the back below junction of spinous and soft dorsal; lower jaw 38-42% length of head; 3-6 epibranchial gill-rakers. Liberia to Sierra Leone .......... buettikoferi. Please note that these i
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