. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ENCEPHALON OF REPTILES. 293 IS shown in the medulla oblongata, which is indicated by a slight tumefaction giving off the fifth, 3,4, 5, 6, seventh, 7, eighth, 8, and ninth pairs of cerebral nerves: the tract is bounded anteriorly by the hypophysis covering the origin of the optic nerves. The continuation of the basal fibres of the hemispheres, p, into the rhinencephalon, E, is shown. In a side view, the several primary divisions of the chelonian brain present the shapes and proportions shown in fig. 192, in Avhich C is t
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ENCEPHALON OF REPTILES. 293 IS shown in the medulla oblongata, which is indicated by a slight tumefaction giving off the fifth, 3,4, 5, 6, seventh, 7, eighth, 8, and ninth pairs of cerebral nerves: the tract is bounded anteriorly by the hypophysis covering the origin of the optic nerves. The continuation of the basal fibres of the hemispheres, p, into the rhinencephalon, E, is shown. In a side view, the several primary divisions of the chelonian brain present the shapes and proportions shown in fig. 192, in Avhich C is the epencephalon, o, the mesencephalon, p the prosence- phalon ; E, the rhinencephalon. The epencephalon includes the medulla oblongata, with the cerebellum. .-.:k. Brain of a Turtle iCIidonc), side view. ecu. In the turtle ( Chelone, fig. 191) the cerebelkmi, c, is slightly raised by the bristle, o, to expose the fourth ventricle, /*, in which the sides of the calamus rise into ' teretial tracts.' The cere- belluna is subelongate in its form, consisting of an arched layer of neurine, smooth externally, of equal thickness throughout, which spreads over a portion of the ventricle. The remainder of that cavity is covered by a vascular plexus, derived from the sides of the medulla oblongata, which forms a sort of valve, and by becoming united to the margin of the cerebellum, com- pletes the roof of the fourth ventricle, which is large and jjro- longed very far back. The optic lobes, O, are smooth, sphe- roidal bodies, on a plane inferior to the cerebellum and cere- brum. Each lobe has its ventricle, c*, which communicates, as shown by the bristle, m, with the fourth ventricle, and likewise with the third ; the ' iter' to which may be seen by divaricating the optic lobes, covered by pia mater reflected down the intersjDace, and by a very thin layer of neurine. From the third ventricle a canal, or ' infundibulum,' is continued down to the hypophysis, and another upward to the ' pinea
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
