. Bulletin of the British Museum (Natural History), Geology. 102 NEOGENE FISHES FROM In type n teeth the occlusal outline is a distorted ovoid, the narrow end of which is thrown into a single high and conical cusp. One face of this cusp (the longest one) slopes more steeply than the others so that, in effect, its apex is situated somewhat eccentrically. A ridge of three low, blunt cusps, one more elongate and discrete than the others, is arranged in a gentle curve, the concave side of which faces the single major cusp (Fig. 22B, a). Beyond this cusp ridge, and at a lower level, is a curvi- lin
. Bulletin of the British Museum (Natural History), Geology. 102 NEOGENE FISHES FROM In type n teeth the occlusal outline is a distorted ovoid, the narrow end of which is thrown into a single high and conical cusp. One face of this cusp (the longest one) slopes more steeply than the others so that, in effect, its apex is situated somewhat eccentrically. A ridge of three low, blunt cusps, one more elongate and discrete than the others, is arranged in a gentle curve, the concave side of which faces the single major cusp (Fig. 22B, a). Beyond this cusp ridge, and at a lower level, is a curvi- linear ridge of about five or six poorly demarcated cusps. It parallels the first ridge and forms the occlusal margin of the crown. There is one well-preserved tooth of this type, and one badly worn specimen. The longest horizontal axis of each tooth measures 12-0 and c 8-0 mm respectively. Type hi teeth have an almost circular occlusal outline. The crown is dominated by a distinct central cusp whose wide but compressed shoulders form a crest extending across almost the complete diameter of the crown. At each margin of the crest there is a low minor cusp forming part of a circlet of similar cuspules that encircles about three-quarters of the crown's margin (Fig. 22B, b). The whole occlusal surface slopes downwards towards the presumed lingual side of the tooth. It is at the lowest point of the crown that the circlet of cuspules is interrupted. The bone of attach- ment is flared away from the vertical axis of the tooth on this lower side. There are three type hi teeth, whose longest horizontal axes measure 9-5, g-o and 5-5 mm respectively. On the basis of tooth outline in Alestes macrolepidotus and Colossoma bidens we would suggest that teeth of type 11 are from the midline of the jaw (that is, the first tooth in the row of each premaxilla), those of type in are next in position and are followed by teeth of type I. On this reckoning, S. lepersonnei would have had at least six teeth
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