. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 42 Bulletin Museum of Comparative Zoology, Vol. 150, No. 2 suprooccipito parietal epioccipital extrascapula intercalar. pterotic exoccipita basioccipita Figure 7. Neurocranium of D. taenia (USNM 206614; mm SL), posterior view. the border of the foramen magnum, ex- ckiding the basioccipital from the fora- men magnum. Ventral to the foramen magnum, the exoccipital bears a wide ar- ticular facet which fonns, with the basi- occipital (see below), a deeply concave articular surface for the notochord. The foramen for
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 42 Bulletin Museum of Comparative Zoology, Vol. 150, No. 2 suprooccipito parietal epioccipital extrascapula intercalar. pterotic exoccipita basioccipita Figure 7. Neurocranium of D. taenia (USNM 206614; mm SL), posterior view. the border of the foramen magnum, ex- ckiding the basioccipital from the fora- men magnum. Ventral to the foramen magnum, the exoccipital bears a wide ar- ticular facet which fonns, with the basi- occipital (see below), a deeply concave articular surface for the notochord. The foramen for the ninth and tenth cranial nerves is a prominent feature of the ex- occipital (Fig. 7). The medial surface of the exoccipital fonns the posterolateral and posterodor- sal walls of a deep cavity which contains the saccular and lagenar portions of the ear. In addition, there is a deep concavity dorsolaterally on the exoccipital in which lies the ampulla at the junction of the posterior portions of the horizontal and posterior vertical semicircular canals. The basioccipital is a single bone which forms the posterior floor of the neurocranium (Figs. 4-7). Anteriorly, the basioccipital extends to a point about midway between the posterior surface of the neurocranium and the anteroventral border of the prootic. Anteroventrally the basioccipital lies dorsal to the parasphe- noid, which is tightly joined to it syndes- motically and synchondrally. The broad- ly concave anterior border of the basioccipital has a synchondral joint with the prootic; the nearly straight dorsal bor- der has a synchondral joint with the ex- occipital. Posteriorly the basioccipital has a deeply concave articular surface for the notochord. The basioccipital fonns the floor of the lagenar capsule. The shape of the basioccipital in me- dial view is illustrated in Figures 5 and 6. There are bilateral, very deep concav- ities in the bone in which lie the saccular and lagenar portions of the ear. The large medial f
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Keywords: ., bookauthorharvarduniversity, bookcentury1900, booksubjectzoology
