. Geological magazine. 172. Dr. R. H. Traquair—On Chondrosteus acipenseroides. 255 bone {pt.) which bifurcates posteriorly, one limb being placedalong the middle, the other along the mesopterygoid is the bone which Sir Philip Egerton has interpreted asmaxilla {op. cit. pi. Ixix. 21), but whose true relations are mostclearly seen in a large number of specimens in the British relations are not obscure even in the specimen figured bySir Philip ; but here, as already explained, he unfortunately mistookthe real maxilla for the lower jaw. As the position of this little
. Geological magazine. 172. Dr. R. H. Traquair—On Chondrosteus acipenseroides. 255 bone {pt.) which bifurcates posteriorly, one limb being placedalong the middle, the other along the mesopterygoid is the bone which Sir Philip Egerton has interpreted asmaxilla {op. cit. pi. Ixix. 21), but whose true relations are mostclearly seen in a large number of specimens in the British relations are not obscure even in the specimen figured bySir Philip ; but here, as already explained, he unfortunately mistookthe real maxilla for the lower jaw. As the position of this littlebone is about the middle of the maxilla and behind the suborbital,we may feel a little surprised at the following statement in thepublished abstract of Mr. Daviss paper:—? From the position of therespective maxillary and premaxillary bones in this (Mr. Daviss)specimen, there can be no further doubt that the small bifurcatedbone of C. acipenseroides, Ag., described as the maxillary bone, isreally the Fig. 5.—Profile of head of Chondrosteus, restored. But if we inquire what this little bifurcated bone reallyis, I answer that it seems to me to occupy, as regards the maxillaand the great palate-plate, a position quite analogous to that of thesmall bone in Acipenser lettered as palatine by Professor W. , but which I have come to look upon as a pterygoid orectopterygoid, for the same reasons which have induced me to regardthe great palate-plate as a mesopterygoid, and as such I haveaccordingly marked it. I have seen no evidence of ossified quadrate or metapterygoidelements. There can be no doubt that the bone interpreted by SirPhilip Egerton as a combined mesotympanic and hypotympanic{symplectic and quadrate of modern nomenclature), is that externalplate appended to the hinder extremity of the maxilla, which I havealready described as the jugal. The mandible is stout, and anteriorly is, like tbe maxilla, stronglycm-ved inwards to meet its fellow of the op
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1864
