. Bulletin of the British Museum (Natural History), Geology. PALAEONISCOID FISHES AND THE CHONDROSTEI Exsc Ssc 173 Ptr. Pop Br Clav 5mm Fig. 22. Phanerorhynchus armatus Gill. Reconstruction of skull in lateral view. are relatively small and square in outline, while the frontals are long with their anterior margins produced into a point thus giving the postrostral a V-shaped in- sertion between the two frontals. On either side of the single median postrostral is a stout, long, nasal element. The nasal is broad and its lateral margin has an emargina- tion (naz) which indicates the posi
. Bulletin of the British Museum (Natural History), Geology. PALAEONISCOID FISHES AND THE CHONDROSTEI Exsc Ssc 173 Ptr. Pop Br Clav 5mm Fig. 22. Phanerorhynchus armatus Gill. Reconstruction of skull in lateral view. are relatively small and square in outline, while the frontals are long with their anterior margins produced into a point thus giving the postrostral a V-shaped in- sertion between the two frontals. On either side of the single median postrostral is a stout, long, nasal element. The nasal is broad and its lateral margin has an emargina- tion (naz) which indicates the position of the posterior nostril. The anterior nostril (naj) lies between the nasal, postrostral and rostro-premaxillo-antorbital. Pos- teriorly the nasal joins the frontal and the dermosphenotic, anteriorly the rostro- premaxillo-antorbital. The postrostral is only slightly convex transversely in its posterior half, but the anterior half of the bone is strongly curved in a transverse as well as longitudinal direction, giving the head a distinct rostrum. Ventrally the postrostral meets the paired rostro-premaxillo-antorbitals. The rostro-premaxillo- antorbital is notched anterio-dorsally (naz) while posteriorly it is ornamented with several backwardly pointing short spines. Dorsally it articulates with the nasal and posteriorly with both the maxilla and infraorbital. The lateral wall of the skull roof comprises two bones, the dermopterotic and the dermosphenotic. The dermopterotic is broad posteriorly but tapers almost to a point anteriorly where it fits between the dermosphenotic and the frontal. The dermo- sphenotic is larger than the dermopterotic and anteriorly meets the nasal. Ventrally. 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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