. Bulletin of the British Museum (Natural History), Geology. FISHES OF THE TRIASSIC 257 tip of the dentary which are twice as long as any other and which are sharply re- curved (P. 15858, Fig. 11). In lateral view the posterior coronoid curves dorsally along the dentary margin. This too bears numerous teeth which are up to 0-5 mm high, and which appear to overlap one another in lateral aspect (, Fig. 10). Sensory canal system. Part of the ethmoid commissure is represented on the anterior process of the antorbital by two groups of three or four shallow pits, similar to those seen on the
. Bulletin of the British Museum (Natural History), Geology. FISHES OF THE TRIASSIC 257 tip of the dentary which are twice as long as any other and which are sharply re- curved (P. 15858, Fig. 11). In lateral view the posterior coronoid curves dorsally along the dentary margin. This too bears numerous teeth which are up to 0-5 mm high, and which appear to overlap one another in lateral aspect (, Fig. 10). Sensory canal system. Part of the ethmoid commissure is represented on the anterior process of the antorbital by two groups of three or four shallow pits, similar to those seen on the infraorbitals of Aestiiarichthys ftdcratus (Gardiner 1969 : 437). No trace can be seen of the anterior branch of the infraorbital sensory canal on the dermosphenotic figured by Wade (1935 : text-fig. 5). The supraorbital sensory canal is not of the normal palaeoniscoid pattern: it runs across the nasal and frontal, but posteriorly it passes onto the dermopterotic (Fig. 10). Often the canal is dis- placed slightly at the suture between the frontal and dermopterotic. In no specimen was the supraorbital canal observed to join the infraorbital canal on the dermopterotic ( Wade 1935 : text-fig. 5). In some ( and , Fig. 12), there is apparent joining of the supraorbital and infraorbital canals, because canals from both sides of the skull are preserved and the canal which appears to run into a right infraorbital canal is in fact a left supraorbital canal. The left infraorbital canal is seen about a millimetre below the right infraorbital canal and the left supraorbital canal does not reach the latter (Fig. 12). Palate. In specimens and (Fig. 10) the palate has been preserved. Its visible upper surfaces have been partly eroded away, revealing the roots of numerous teeth. The endopterygoid is wide anteriorly, and bears tiny teeth which soc(r) soc na(r) ant pmx. 4mnn » 1 1 L Fig. 12. Brookvalia gracilis Wade. : right side unless otherwise in
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