. Bulletin of the British Museum (Natural History), Geology. i6 THE HEAD OF DIPTERUS V A L E N CIE N N E SI The sensory canals are perfectly orthodox, as may be seen in the revised diagram (Text-fig. 13), but the series of lateral line bones show two interesting deviations, apart from the absence of M. A single bone occupies the space not only of M but of both the " L " bones and there is clearly only a single centre of growth, which from its central position is judged to be that of the middle bone of the three, L^. There is. Fig. 18. Diptenis valenciennesi S. & M. Skull-roof of
. Bulletin of the British Museum (Natural History), Geology. i6 THE HEAD OF DIPTERUS V A L E N CIE N N E SI The sensory canals are perfectly orthodox, as may be seen in the revised diagram (Text-fig. 13), but the series of lateral line bones show two interesting deviations, apart from the absence of M. A single bone occupies the space not only of M but of both the " L " bones and there is clearly only a single centre of growth, which from its central position is judged to be that of the middle bone of the three, L^. There is. Fig. 18. Diptenis valenciennesi S. & M. Skull-roof of large head with plates Z-A-Z added, showing external pores of sensory canals on right side, and restoration of the canals on the left side, based on Figs. 14, 15. [cf. Jarvik 1950, text-fig. 6 ; Gross 1956, text-fig. 13B; 0rvig 1961, text-fig. 7B). Coast near Thurso, Caithness. XI-5. A, underside of snout of similar specimen. Toldale Quarry, between Thurso and Reay, Caithness. Xi-5. ifc, infraorbital canal, mil, main lateral line. soc, supraorbital canal and Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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