^34 Journal of Comparative Neurology. 



pressions, which are impressed upon the axial lobe, and may 

 or may not be obvious before the removal of the pallium. 

 Three of these are especially constant. First, tlic frontal 

 Jissiirc^ separating the mesaxial lobe superficially from the 

 remainder of the cerebrum. This fissure begins upon the 

 cephalic or ventral surface and extends parallel to the longi- 

 tudinal fissure a longer or shorter distance upon the dorsal 

 surface. The occipital fissure occupies an analogous position 

 upon the occipital region, and in extreme cases unites with 

 the frontal to form an occipito-frontal groove. The third 

 fissure is the dorsal portion of the Sylvian fissure^ and extends 

 a variable distance toward the occipito-frontal. 



By the aid of these external landmarks and the variations 

 in internal structure, a few pretty well-marked regions of the 

 axial lobe may be conveniently designated. The mesaxial 

 lobe is that region bordering the longitudinal fissure and 

 limited laterally by the frontal fissure. The central lobe is 

 an ill-defined region, with few large spindle cells lying in the 

 central and ventral portions of the cerebrum. In some cases 

 there is a w^ell-defined line of demarkation between this and 

 adjoining areas. It is in the ventral portion of this lobe that 

 the peduncles enter the cerebrum, and it may be looked upon 

 as forming in a special sense the homologue of the striatum. 

 The lateral or parietal lobe embraces the lateral portions of 

 the cerebrum, and, though frequently imperfectly defined 

 externally, difters in cellular structure sufficiently to make its 

 recognition possible. A small lobule lying between the 

 Sylvian and occipital fissures may be called the ciineus with- 

 out implying any homologies with higher brains (see Fig. i, 

 Plate XIX). An occipital lobe may be recognized in the 

 caudad projection lying adjacent to the habenoe, and a tetn- 

 poral lobe upon the caudo- lateral aspects behind the Sylvian 

 fissure. There is a caudo-ventral projection which is invaria- 

 bly present, and, from its being the starting-point of the 

 posterior part of the pallium, may be compared to a hippo- 

 campus, and will be referred to as the hippocampal lobule. 



