. Bulletin of the British Museum (Natural History). NC / ,- ' g. ,y/^^^<^ 1 mm. Fig. 5. Right frontal and nasal seen somewhat obliquely from above, to show supra- orbital laterosensory region bridges (Fbs and Fbo), the nasal lamina (Nlm) and the groove (Gr) leading from the dermosphenotic to the supraorbital laterosensory chamber. Anteriorly, this bridge ends near the medial end of the transverse one (Text-figs 3 and 5). Further support for the skin roof of the supraorbital cavern is provided anteriorly by the process derived from each nasal (see above, p. 220). Besides providing sup-
. Bulletin of the British Museum (Natural History). NC / ,- ' g. ,y/^^^<^ 1 mm. Fig. 5. Right frontal and nasal seen somewhat obliquely from above, to show supra- orbital laterosensory region bridges (Fbs and Fbo), the nasal lamina (Nlm) and the groove (Gr) leading from the dermosphenotic to the supraorbital laterosensory chamber. Anteriorly, this bridge ends near the medial end of the transverse one (Text-figs 3 and 5). Further support for the skin roof of the supraorbital cavern is provided anteriorly by the process derived from each nasal (see above, p. 220). Besides providing sup- port for the roof, these laminae serve as a lateral wall for the anterior part of the cavern, and in this way connect the supraorbital and nasal laterosensory canals. Further connection between these parts of the system is provided by a short bony tube opening anteriorly into the floor of the nasal, and posteriorly into the groove formed between the supraorbital and medial parts of the frontal. On the ventral face of each frontal there is a narrow but prominent ridge following the course of the postorbital groove for the lateral-line (see above). The ridge is directed somewhat medially. Along most of its length it contacts the pterosphenoid, while ventrally it articulates with the sphenotic. Nerves supplying the posterior frontal neuromasts are carried in bony tubes on the ventral face of the bone. Two short tubes open close together into the posterior part of the supraorbital groove; a third, much longer tube runs back to the temporal region. The latter canal opens at the posterior base of the parasagittal bridge. Its origin, on the ventral face of the frontal, lies behind the ridge described above, where- as the two supraorbital tubes originate in front of the ridge. Nerves supplying the anterior frontal neuromasts of the supraorbital line are not enclosed in tubes, but gain access to the cavern through two foramina lying in the anterior parts of the supraorbital groove. The
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Keywords: ., 1968, boo, bookauthorbritishmuseumnaturalhistory, bookcentury1900
