. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates. 200 COMPARATIVE ANATOMY •myelcnccphalon1 (primary hind-brain). The telencephalon usu- ally gives rise to a pair of lobes, the cerebral hemispheres, and the mid-brain to a pair of optic lobes or corpora bigemina dorsally, and to two longitudinal bands, the crnra cerelri, ventrally. The meten- cephalon is also spoken of as the cerebellum, and the myelencephalon as the bulb or medulla oblongata. From the secondary fore-brain paired olfactory lobes 2 are given off anteriorly, and its floor or basal TIE Z ZimCJIKS1!) JIK. FIG.
. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates. 200 COMPARATIVE ANATOMY •myelcnccphalon1 (primary hind-brain). The telencephalon usu- ally gives rise to a pair of lobes, the cerebral hemispheres, and the mid-brain to a pair of optic lobes or corpora bigemina dorsally, and to two longitudinal bands, the crnra cerelri, ventrally. The meten- cephalon is also spoken of as the cerebellum, and the myelencephalon as the bulb or medulla oblongata. From the secondary fore-brain paired olfactory lobes 2 are given off anteriorly, and its floor or basal TIE Z ZimCJIKS1!) JIK. FIG. 149.—LONGITUDINAL SECTION THROUGH THE SKULL AND BRAIN OK AN (IDEAL) VERTEBRATE EMBRYO. (In part after Huxley.) Be, basis cranii; Cc, central canal of spinal cord ; Ch, notochord ; HC, posterior commissure ; HH, cerebellum (metencephalon, secondary hind-brain) ; MH. mid-brain (mesencephalon); NH, primary hind-brain (myelencephalonJ ; NH1, nasal cavity; SD, roof of skull; VH, secondary fore-brain (telencepha- lon), showing the corpus striatum (Cx) at the base, and the olfactory lobe (Olj) anteriorly; ZH, diencephalon (primary fore-brain), which has given rise dorsally to the pineal body (epiphysis, Z), and ventrally to the infundi- bulum (7), to which the pituitary body (hypophysis, H) is attached : anteriorly to this is seen the optic nerve (Opt), arising from the optic thalamus (Tho). portion becomes thickened to form a large " basal ganglion/' the corpus striatum, while its peripheral part is distinguished as the " mantle " or pallium (Fig 149).3 The pallial region undergoes an important process of develop- ment in passing upwards from lower to higher forms, gradually becoming differentiated histologically into a layer of cortical gr«i/ matter of great physiological importance,the relative differentiation of which stands in close relation to the mental development of the animal. The telencephalon reaches its greatest perfection in Mammals, more especially
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