. Bulletin of the British Museum (Natural History), Geology. 398 BUCHANOSTEID ARTHRODIRES especially must have been massive. It follows the curve of the orbit and turns upwards giving off as it does a postero-ventral process {—cf. Stensio 1963 : 232, text-figs 51C, 70, 77). Almost immediately above this the palatine is pierced by a very large foramen or arch (&.F2), and shortly above this the seating of the auto- palatine part is separated from that of the middle part of the palatoquadrate by a wide gap or broken arch [p. ¥2,3)- This gap is possibly for the passage of the maxillary a
. Bulletin of the British Museum (Natural History), Geology. 398 BUCHANOSTEID ARTHRODIRES especially must have been massive. It follows the curve of the orbit and turns upwards giving off as it does a postero-ventral process {—cf. Stensio 1963 : 232, text-figs 51C, 70, 77). Almost immediately above this the palatine is pierced by a very large foramen or arch (&.F2), and shortly above this the seating of the auto- palatine part is separated from that of the middle part of the palatoquadrate by a wide gap or broken arch [p. ¥2,3)- This gap is possibly for the passage of the maxillary and mandibular nerves, of which the former turned forwards and, joined by the lateral buccal nerve, passed through the lower arch {). The seating of the middle part runs near and roughly parallel with the top of the plate and is only half the width of the autopalatine attachment, and in a fragment from a somewhat larger fish () the whole surface is seen to have been covered in bone. The front of this margin at the orbit is broadened with large inner lateral denticles or pegs for attachment to the skull-roof [, Text-fig. 15). In general the arrangement of the palatoquadrate in this region bears a very fair resemblance to Stensio's 'Tentative restoration' in Kujdanowiaspis (Stensio 1963 : 123-5, 199. 206, text-figs 39^, B, 40).. Fig. 16. Parabiichanosteus vniirnimbidgeensis (White). Right sub-marginal plate with cross-sections at a&, cif. X3. The only other part of the head identified in the collections, the submarginal plate, is represented by a single but complete specimen from the right side (Text-fig. 16). It is thin and internally concave, 370 mm long and 10 mm wide at the maximum. Both margins are gently curved, the lower concave except at the back, the upper convex, especially in front, and in spite of the universal tubercular ornament it shews a groove along the marginal contact. At the back it is cut away for the projection of the postmargin
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