A treatise on zoology . dibulum ; , lateral cavity; Li, lobus inferior; , lamina terminalis; m, medullaoblongata ; , olfactory lobe ; os, olfactory tract; , ojitic lobe ; jyr, ijrofundus nerve ; psji,prespiracular branches of facial; , superior ophthalmic branches of facial and trigeminal;, spinal cord ; , saccus vasculosus ; th, diencephalon (thalamencejihalon) ; , third ven-tricle ; r, vagus nerve ; , ventral root of spinal ner\e. large size and complicated structure in the higher Pisces and higherTetrapoda. The mid-brain remains undivided. The cavity itencloses
A treatise on zoology . dibulum ; , lateral cavity; Li, lobus inferior; , lamina terminalis; m, medullaoblongata ; , olfactory lobe ; os, olfactory tract; , ojitic lobe ; jyr, ijrofundus nerve ; psji,prespiracular branches of facial; , superior ophthalmic branches of facial and trigeminal;, spinal cord ; , saccus vasculosus ; th, diencephalon (thalamencejihalon) ; , third ven-tricle ; r, vagus nerve ; , ventral root of spinal ner\e. large size and complicated structure in the higher Pisces and higherTetrapoda. The mid-brain remains undivided. The cavity itencloses is known as the aqueductus of Sylvius, or and at the sides the wall thickens into the prominent opticlobes, from which pass fibres to the optic tract. Below, a bundleof fibres develops into the crura cerebri. From this mesencephalonissue the oculomotor and pathetic nerves. DRAIN 15 From the primitive fore-brain are differentiated a posteriordiencephalon (thalamencephalon) and an anterior secondary fore-. Dorsal view of the brain of Heptanehmcinermi. (Fi-om Gegenbaur, Vcnjl. Anat. IVirMtiere.)Ac, auditory nerve ; F, facial, Gp, glossopharyngeal; H, cerebellum ; M, optic lobe ; Ms, spinalcord ; JV, medulla, also nasal sac ; 0, optic nerve ; Po, olfactory tract ; Tr, trigeminal nerve ;V, fore-brain ; Vg, vagus nerve ; Z, diencephalon ; a and ft, branches of facial and trigeminal;at, abducens ; hp, (hypoglossal) occipito-spinals ; I, olfactory lobe,; om, oculomotor ; v, originof vagus roots. brain, the telencephalon. The diencephalon, bounded behind by theposterior commissure, is crossed above l)y the superior commissure 16 BRAIN (habenular). Between these two tracts of fibres are the epiphysialoutgrowths. At the anterior limit the thin non-nervous portionsof the roof form a choroid plexus, sinking down behind theparaphysis, and projecting into the large 3rd ventricle as a velumtransversum (permanent in the lower and transient in the higherforms). At the sides aris
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
