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Show 1893.] BRAIN OF THE AFRICAN ELEPHANT. 313 T-shaped fissure running at right angles to the longitudinal axis of the brain; one of these, but I am not sure which, is probably the pre-Sylvian fissure (Plate XXIII. fig. 1, P.s). The front aspect of the brain is marked by two principal fissures, of which the innermost (that nearest the interhemispheral sulcus) appears to me to be the anterior termination of a more or less strongly marked furrow running on the dorsal aspect of the hemisphere for more than the anterior half at a distance of rather less than an inch from the interhemispheral sulcus. The second of the two fissures observable on the frontal lobe of the brain is almost as far from the last mentioned as from the Y-shaped fissure referred to above. This fissure seems also to be the anterior end of another longitudinal furrow, which curves round posteriorly and is continuous with the first of the two fissures dividing the temporal lobe of the brain longitudinally. The temporal lobe is divided by two furrows, of which the anterior is approximately equidistant from the anterior margin of the temporal lobe and from the posterior furrow, into three gyri-an antero-temporal, a medio-temporal, and a postero-temporal. The posterior temporal fissure (Plate XXIII. fig. 1, P.t) curves over the hemisphere and divides off an occipital lobe, becoming continuous with the sulci of the inner face of the hemisphere. The anterior temporal furrow bends round and forms the posterior of the three branches of the Sylvian. Left Hemisphere. The left hemisphere of the brain (Plate XXIII. fig. 2) shows many detailed differences from the right; in more complicated brains there is of course usually such an asymmetry; the existence of this asymmetry, however, perhaps enables one to abstract from a consideration of both halves of the brain a list of the more important furrows. On the upper surface of the hemispheres the two longitudinal furrows are not recognizable anteriorly; they are lost by the more marked cross furrowing. Posteriorly, however, the outer of the two is very deep, and, therefore, conspicuous ; it is continuous, as on tbe right side, with the middle temporal fissure. Both the temporal sulci are as pronounced on the left side as on the right. The fissure of Rolando, however, if I a m right in so identifying it, is by no means so extensive on the left side. It seems to be divided into two tracts, of which that continuous with the Sylvian is the deepest; tbe upper half comes to within about the same distance of the internal margin of the hemisphere. Anteriorly there are the same two Y-shaped fissures, of which the first (counting from behind forwards) is, as on the right hemisphere, the deeper. The temporal fissures are as on the right side. Cerebellum. The cerebellum is neither figured nor described by Krueg. As shown in the accompanying drawing (Plate XXII.), it has a narrow median lobe, which is visible in the cerebellum only as seen from |
