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Show 1869.] ANATOMY OF PROTELES. 479 backwards at a right angle, and then descends to the temporal lobe, its posterior limb being twice the breadth of the anterior, and indented by a vertical fissure parallel to the Sylvian. The second, or middle gyrus (m mi), surrounds the last in the whole of its extent, commencing in the frontal and ending in the hinder part of the temporal lobe. At its posterior superior angle it is partly interrupted in front by a short sulcus, which runs upwards and backwards from the posterior part of the main sulcus separating the inferior from the middle gyrus. The third, or superior gyrus (s s) may be considered to commence in the supraorbital region*, whence it extends along the upper part of the hemisphere, bordered within by the great longitudinal fissure, as far as its posterior extremity. Anteriorly it is broad, and is sharply folded on itself in a sigmoid manner,-first winding round the supraorbital sulcus (O), and then round the crucial sulcus (C), which runs almost directly outwards from the great longitudinal fissure for the distance of half an inch, very near the anterior end of the hemisphere. On the inner surface of the hemisphere (fig. 4) the superior gyrus is seen to extend completely round the border, bounded below by the calloso-marginal sulcus, and interrupted near the front by the crucial sulcus. It terminates by joining the middle external sulcus at the posterior apex of the hemisphere. It has several indentations on its surface, notably a longitudinal one near its hinder end. On the inner surface of the hemisphere, below the calloso-marginal sulcus, is the " internal" gyrus of Leuret (fig. 4, h h), which surrounds the corpus callosum, and may be traced backwards and downwards, around the great opening through which the crus passes into the hemisphere to form the great prominence of the temporal lobe. As the sulcus on the concave side of the lower part of this gyrus forms the hippocampus major, it may be called the hippocampal gyrus. There are thus four distinct gyri-an inferior, middle, and superior external, and an internal or hippocampal gyrus. I am not aware of any published description or figure of the brain of Hycena ; but a specimen is preserved in the Museum of the Royal College of Surgeons, the species, unfortunately, not recorded. This brain has the gyri and sulci of the cerebral hemisphere arranged on exactly the same plan as those of Proteles; but being a larger brain, the secondary sulci are rather more marked. The whole brain is rounder in form, both breadth and height being greater proportionally to length than in Proteles, and consequently the three external gyri make higher and shorter arches. The cerebral convolutions of the Felidce are also arranged on the same pattern, but are rather more complex f. On the other hand, * Leuret determines this portion of the brain-surface as a distinct (supraorbital) gyrus. t The uniform character of the cerebral convolutions in various species of Felidce was pointed out by O w e n (" O n the Anatomy of the Cheetah," T. Z. S, vol. i. p. 133). Much valuable information and some excellent figures of the brains of the Carnivora are contained in Leuret's ' Anat. Comp. du Systeme Nerveux,' vol. i. |