. Geological magazine. n one specimen of Morosaurus, a similaropening has been observed, but in other Sauropuda, the parietalbones, even if thin, are complete. The suture between the parietalsand frontal bones is obliterated in the present skull, and the union isfiim in all the specimens observed. The frontal bones in Biplodocus are more expanded transversely thanin the other Sauropoda. They are thin along the median portion, butquite thick over the orbits. The nasal bones are short and wide, and the suture between themand the frontals is distinct. They form the posterior boundary ofthe large
. Geological magazine. n one specimen of Morosaurus, a similaropening has been observed, but in other Sauropuda, the parietalbones, even if thin, are complete. The suture between the parietalsand frontal bones is obliterated in the present skull, and the union isfiim in all the specimens observed. The frontal bones in Biplodocus are more expanded transversely thanin the other Sauropoda. They are thin along the median portion, butquite thick over the orbits. The nasal bones are short and wide, and the suture between themand the frontals is distinct. They form the posterior boundary ofthe large nasal opening, and also send forward a process to meet theascending branch of the maxillary, thus forming in part the lateralborder of the same aperture. The nasal opening is very large, subcordate in outline, and is par-tially divided in front by slender posterior processes of the pre-maxillaries. It is situated at the apex of the skull, between theorbits, and very near the cavity for the olfactory lobes of the Fig. 4.—Front view of the skull of (one-sixth nat. size). 102 Prof. 0. C. Marsh—A Neiv American Jurassic Dinosaur. The premaxillaries (Fig. 4) are narrow below, and with, the as-cending processes very slender andelongate. Along the median linethese processes form an obtuseridge, and above they project intothe nasal opening. Each pre-maxillary contains four functionalteeth. The maxillaries are very largelydeveloped, more so than in mostother Isnown reptiles. The denti-gerous portion is very high, andslopes inward. The ascending pro-cess is very long, thin and flattened,inclosing near its base an ovalforamen, and leaving a large un-ossified space posteriorly. Above,it meets the nasal and prefrontalbones. Along its inner border fornearly its whole length, it uniteswith the ascending process of thepremaxillary. Each maxillary con-tains nine teeth, all situated in theanterior part of the bone (Fig. 1). Along their upper margin, on the inner surface, the
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