. Bulletin of the British Museum (Natural History) Zoology. . Fig. 10 Frontal and temporal sensory canals in A, Ompok bimaculatus (BMNH :171-8); B, Kryptopterus bleekeri (LILI 89030); C, Hemisilurus heterorhynchus BMNH :161. extended mentomeckelian cavity; a small coronomeckelian bone lies in the posterior cavity of the anguloarticular from which the Meckelian cartilage extends forward. The anguloarticular is deep, its dorsal border lying at the same level as that of the dentary, forming a smoothly rounded coronoid process. The anterior border of the anguloarticular extends
. Bulletin of the British Museum (Natural History) Zoology. . Fig. 10 Frontal and temporal sensory canals in A, Ompok bimaculatus (BMNH :171-8); B, Kryptopterus bleekeri (LILI 89030); C, Hemisilurus heterorhynchus BMNH :161. extended mentomeckelian cavity; a small coronomeckelian bone lies in the posterior cavity of the anguloarticular from which the Meckelian cartilage extends forward. The anguloarticular is deep, its dorsal border lying at the same level as that of the dentary, forming a smoothly rounded coronoid process. The anterior border of the anguloarticular extends well forward into the mentomeckelian cavity of the dentary. The articulatory surface is complex, with a large, inwardly angled facet (Fig. 15C). In keeping with the condition in other members of the Siluridae and the majority of siluroids examined, the pre- maxilla of Belodontichthys is approximately half the length of the lower jaw. The laterally exposed surface, the part not covered by the ethmoid cornua, is 45% of its total length. In comparison, the exposed surface in other silurid taxa ranges from 25% {Kryptopterus apogon) to 40% {Ompok bimaculatus). The premaxillary ascending process, which contacts the lateral margin of the ethmoid cornua, is a rather prominent, obliquely transverse process in Belodontichthys and Ompok, whereas in other Siluridae it rises gently to a promontory situated in the centre of the bone (Figs 14A-D). The lower jaw of Belodontichthys differs markedly from that in other genera of Siluridae and the majority of siluroids in having only a slight inward curvature at the symphysis (Fig. 15D); in other taxa the united rami form a broad crescent or a U-shape. The dentary differs little in its length and depth from that in other Siluridae and, like most, has 5 openings in the sensory canal. Silurus and Wallago have between 6 and 10. The dentary canal openings in Hemisilurus and Ceratoglanis (Bornbusch & Lundberg, 1989) are extensive and separated
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