. Bulletin of the British Museum (Natural History), Geology. EVOLUTION OF THE SNOUT IN ACTINOPTERYG1ANS 279 sphenotic passes forward to meet the nasal. The infraorbito-supraorbital lies alongside the dermosphenotic and overlaps it to a slight degree. Anteriorly the infraorbito-supraorbital also joins the nasal. The postrostral is only slightly curved from side to side in its posterior half, giving but a slight convexity to the dorsal surface ; however, the anterior half of the bone is strongly curved in a trans- verse as well as a longitudinal direction, giving the head the typical palaeonisci
. Bulletin of the British Museum (Natural History), Geology. EVOLUTION OF THE SNOUT IN ACTINOPTERYG1ANS 279 sphenotic passes forward to meet the nasal. The infraorbito-supraorbital lies alongside the dermosphenotic and overlaps it to a slight degree. Anteriorly the infraorbito-supraorbital also joins the nasal. The postrostral is only slightly curved from side to side in its posterior half, giving but a slight convexity to the dorsal surface ; however, the anterior half of the bone is strongly curved in a trans- verse as well as a longitudinal direction, giving the head the typical palaeonisciform profile, that is a distinct rostrum. The radiation centre of the bone lies in its most arched part, in other words that region which forms the anterior tip of the rostrum. Ptr. Exsc Ssc , 10mm , Fig. 6. Nematoptychius greenocki (Traquair). Dorsal view of skull roofing bones. From , and The nasal is stout and broad and its lateral margin forms together with the dorsal margin of the antorbital a distinct emargination (na2) which indicates the position. 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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