. Bulletin of the British Museum (Natural History). Zoology . EVOLUTION OF A CICHLID SPECIES FLOCK 59. Fig. 31. Haplochromis bloyeti. Neurocranium and lower jaw, in left lateral view. (Scale = 3 mm.) pallidus some median teeth are slightly enlarged. A sixth species, H. cinereus, is osteologically one of this group, but differs in having a predominance of unicuspid over bicuspid outer jaw teeth, even in fishes at a size where bicuspids predominate in other species (Greenwood, i960). Because of their generalized cranial anatomy it is impossible to determine the interrelationships of
. Bulletin of the British Museum (Natural History). Zoology . EVOLUTION OF A CICHLID SPECIES FLOCK 59. Fig. 31. Haplochromis bloyeti. Neurocranium and lower jaw, in left lateral view. (Scale = 3 mm.) pallidus some median teeth are slightly enlarged. A sixth species, H. cinereus, is osteologically one of this group, but differs in having a predominance of unicuspid over bicuspid outer jaw teeth, even in fishes at a size where bicuspids predominate in other species (Greenwood, i960). Because of their generalized cranial anatomy it is impossible to determine the interrelationships of these six species ; all could be cognate. However, except for H. pallidus all species have the preorbital skull face slightly more decurved than in the presumed ancestral type, with which H. pallidus is virtually identical. Anatomically, it is interesting to see amongst these fishes a representation, in embryo as it were, of many characters that are developed in various characteristic ways among more specialized trophic groups. For instance, there are the unicuspid teeth of H. cinereus (but see below), the incipient development of enlarged pharyngeal teeth in H. pallidus, and a basic syncranial 'bauplan' that, through differential growth of certain elements (or regions in the case of the neurocranium), provides the starting point for the different types found in other trophic groups. None of the species considered so far has adults exceeding a length of more than 105 mm. Haplochromis saxicola is, superficially, like the foregoing species (cf Text-figs 3 with 8 and 9). However, its neurocranial morphology departs from the basic type towards that of some piscivorous species (Text-figs 34 and 68). That is, the pre- orbital region is more elongate (as is the entire skull anterior to the brain case), its dorsal profile is not noticeably decurved and it slopes downwards less steeply, and there is a reduction in the depth of the brain-case region. The jaw dentition too differs somewh
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