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There is some slight evidence of a connexion between this sense and a region of the hippocampal gyrus near to but behind that related to smell.

Below the calcarine fissure is a gyrus called the gyrus lingualis, and this is bounded below by another true fissure, the collateral, which runs parallel to the calcarine, but is continued much farther forward into the temporal lobe and so forms the lower boundary of the hippocampal gyrus.

It will thus be seen that the hippocampal gyrus is continuous posteriorly with the callosal gyrus above by means of the isthmus, and with the gyrus lingualis below.

Anteriorly the fissure is arrested by the recurved process of the upper part of the hippocampal gyrus, called the uncus, and in front of this a slight sulcus, the incisura temporalis, marks off the temporal pole or tip of the temporal lobe from the region of the uncus.

The hippocampal gyrus is bounded above by the dentate or hippocampal fissure which causes the hippocampus major in the descending cornu and so is a complete fissure.