. Bulletin of the British Museum (Natural History) Geology Supplement. n6 ELOPIFORM FISHES. pto f m f uv Fig. 56. Osmeroides latifrons Woodward. Neurocranium in posterior view, This and Text-figs. 57 and 58 from P. 11190. very large and the ridge which forms the medial margin in all Osmeroides species is particularly well developed here. The intercalar was not seen but the surface mark- ings on the exoccipital and pterotic suggest that it was of limited size (Text-figs. 56, 57 and 58). The lateral surface of the neurocranium shows a large otic bulla and a deep sub- temporal fossa. Bot
. Bulletin of the British Museum (Natural History) Geology Supplement. n6 ELOPIFORM FISHES. pto f m f uv Fig. 56. Osmeroides latifrons Woodward. Neurocranium in posterior view, This and Text-figs. 57 and 58 from P. 11190. very large and the ridge which forms the medial margin in all Osmeroides species is particularly well developed here. The intercalar was not seen but the surface mark- ings on the exoccipital and pterotic suggest that it was of limited size (Text-figs. 56, 57 and 58). The lateral surface of the neurocranium shows a large otic bulla and a deep sub- temporal fossa. Both of these structures are developed to a greater degree than in the type-species. Indeed, the subtemporal fossa is so deep that it severely restricts the lumen of the post-temporal fossa. Also seen upon the lateral face of the prootic is a prominent ridge of bone which passes antero-ventrally from the level of the pars jugularis. This ridge, which provided a site of origin for branchial musculature, is present but less pronounced in other species of Osmeroides. The trigemino-facialis region is basically similar to that of the type-species, but there are two small differences. Firstly, the profundus ciliaris of 0. latifrons leaves the cranial cavity by a separate foramen, whereas in 0. lewesiensis that nerve ran out from the cranial cavity with the trigeminal nerve. The second difference concerns the path taken by the orbital artery. The condition in 0. lewesiensis has been described (p. 99) and is quite typical of elopiforms. In 0. latifrons (as represented by ) an unusual condition existed. The orbital artery pierced the lateral face of the prootic and turned antero-dorsally to pass into the orbit immediately beneath a small bridge of bone, without taking its usual path through the pars jugularis. The path of the orbital artery presumably resulted in the efferent hyoidean branch looping back into the pars jugularis before running out of the prootic with the hyo
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