The annals and magazine of natural history : zoology, botany, and geology . ramen is a smallforamen opening upwards in the lateral wall of the have not been able to trace the course of this opening, butthink it probably merely venous ; it is certainly not a nerve-exit. In front of these foramina is a large hole of irregularshape in the wall and base of the brain-case. The posteriorpart of this is the foramen for the IX., X., and XL nerves ;the rest is the opening into the vestibule. Immediately in front of the opening lies a very smallcanal—the aqueductus fallopii—which passes straight
The annals and magazine of natural history : zoology, botany, and geology . ramen is a smallforamen opening upwards in the lateral wall of the have not been able to trace the course of this opening, butthink it probably merely venous ; it is certainly not a nerve-exit. In front of these foramina is a large hole of irregularshape in the wall and base of the brain-case. The posteriorpart of this is the foramen for the IX., X., and XL nerves ;the rest is the opening into the vestibule. Immediately in front of the opening lies a very smallcanal—the aqueductus fallopii—which passes straight down-wards through the prcotic. Above the internal auditorymeatus is a large deep fossa subarcuata: this passes back-wards andoutwards, and has a smoothly rounded end ; it isseparated from the ear by a thin horizontal flange of bone, Skull, Brain, cbc. o/Diadcmodon. 219 notched at the back so as to allow of a connection betweenthe two organs. Above the processus anterior inferior prootici is a notchfor the V. nerve, above and in front of which the prootic is Fig. Posterior part of the brain-cavity of Diademodon, slightly diagrammatizedfrom the type-skull of D. entomophonus. X 1|. — opening of the canal for the ductus endolymphaticus intothe brain-cavity. subarcuatn. />>?/. = vestibularcavity, p and v, foramina for veins. V, YII, IX, X, XI, XII,foramina for exit of the corresponding cranial nerves, carried forward as a long process covered externally by thealisphcnoid. In the suture between this part of the prooticand the parietal is a venous foramen opening outward intothe sinus-canal. Bones of the Brain-case. The basioccipital and basisphenoid are not separated bysuture ; they are in the cerebellar region very shallow bones,deepening in front until, at the pituitary fossa, the basi-sphenoid is transformed into a deep narrow plate, whichcarries the laterally directed basipterygoid processes, This specimen shows quite clearly that n
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Keywords: ., bookcentury1800, bookdec, booksubjectnaturalhistory, bookyear1838
