. The Ceratopsia. Ceratopsia. ^^^^" 18 THE Fig. 9.—Occipital region of type of Tri- ceratops ftabellatus, No. 1821, Yale Mu- seum, seen obliquely from below. /, Frontals; pf, postfrontals; as, alisphe- noids; exo, exoccipitals; bo, basioccipi- tals; bs, basisphenoids; spt, surface for contact with pterygoids; ol, exit for olfactory nerve; mec, median eustachian canal. One-eighth natural size. lobe through a deep fossa, which doubtless lodged the pituitary body. They probably trans- mitted the carotid arteries. One of these foramina is shown at ca in fig 8. Anteriorly the basi
. The Ceratopsia. Ceratopsia. ^^^^" 18 THE Fig. 9.—Occipital region of type of Tri- ceratops ftabellatus, No. 1821, Yale Mu- seum, seen obliquely from below. /, Frontals; pf, postfrontals; as, alisphe- noids; exo, exoccipitals; bo, basioccipi- tals; bs, basisphenoids; spt, surface for contact with pterygoids; ol, exit for olfactory nerve; mec, median eustachian canal. One-eighth natural size. lobe through a deep fossa, which doubtless lodged the pituitary body. They probably trans- mitted the carotid arteries. One of these foramina is shown at ca in fig 8. Anteriorly the basisphenoidal processes are received into deep pockets en surfaces of the thin but widely expanded posterior wings of the pterygoids. The alisphenoids, including also the parasphenoids, with which they are so completely fused, even in young individuals, as to render the latter elements indistinguishable, are extremely irregular in form. They are firmly coossified with one another and with the exoccipitals and the basisphenoid. Together with the latter element they usually form the entire anterior portion of the brain case, save only the extreme anterior portion of the superior border, which in some instances is formed by the anterior projection of the united postfrontals. Supero-posteriorly the alisphenoids articulate with the supraoccipital and supero-anteriorly with the postfrontals. Just beneath the lateral union of the supraoccipital and post- frontals the alisphenoids are developed into a strong lamina or buttress, which gives greater support to this region. Anteriorly the coossified alisphenoids and basisphenoid are embraced by the vomers and the posterior projections of the palatines, as is well shown in fig. 24, from the type of Triceratops horridus, No. 1820 of the Yale Museum collections, though not so apparent in the type of T. fiahellatus, No. 1821 of the same museum, in which these parts are less perfectly preserved. In the type of T. jlabellatus the o
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherwashingtongovtprin
