104 MR. FLOWER ON THE BRAIN OF THE JAVAN LORIS. 



rupted in the middle line by a slight divergence from each other of the occipital 

 extremities of the hemispheres, distinct even before removal from the cranial cavity. 

 The sulci, though few, are well marked and tolerably symmetrical. The general surface 

 of the brain is very uneven, being raised into strongly pronounced, sinuous gyri, the 

 impression of which is very distinct on the inner surface of the calvarium. There is no 

 appearance of that want of symmetry both of size and form, in the two hemispheres, 

 described and figured by Vrolik. Projecting anteriorly to the extent of one-fifth of an 

 inch beyond the cerebral hemispheres, are the olfactory lobes, of considerable vertical 

 depth, but compressed laterally and pointed in front. Projecting posteriorly is a very 

 narrow edge of the cerebellum, most visible in the middle line, both on account of its 

 own greater prominence at this part, and because the widening out of the termination 

 of the great longitudinal fissure of the cerebrum allows more of its upper surface to 

 be seen. 



When seen from one side, the upper contour of the brain forms a low flattened arch, 

 the greatest point of elevation being a httle way behind the centre (fig. 3). The anterior 

 or frontal lobe is much depressed, and excavated below to make room for the orbital 

 plates of the frontal bone. The temporal lobes, distinctly marked off from the last by 

 the Sylvian fissure, are moderately full, and make a well-marked projection downwards 

 and forwards. The occipital lobes are short and of little vertical depth, being hollowed 

 below for the cerebellum, the greater part of which they cover. 



The sulci of the cerebral hemispheres are^ : — A. On the outer face (figs. 1 & 3). 1 . The 

 fissure of Sylvius (e, e), distinctly marked, directed obliquely upwards and backwards 

 to the middle of the upper surface of the hemisphere, where it makes a slight change 

 in direction, continuing to extend backwards, but almost parallel to the great longi- 

 tudinal fissure. In the first portion of its course, it is as nearly as possible parallel to 

 the inferior margin of the temporal lobe. It divides the whole hemisphere into two 

 tolerably equal parts, the anterior containing the frontal and parietal, the posterior the 

 temporal and occipital lobes. On separating its lips, no distinct median lobe, or 

 insula, could be traced. 2. A distinctly marked sulcus (/) on the temporal lobe, 

 posterior and parallel to the last, corresponding to the " antero-temporal " of the 

 higher Quadrumana {"scissure parallele" of Gratiolet). 3. A small sulcus running 

 in a transverse direction on the upper surface of the hemisphere, at the junction of the 

 parietal and occipital lobes, recalling the " temporo-occipital " {scissure perpendiculaire 

 externe) of the Quadrumana, which fissure is, however, wanting in the smaller American 

 Apes, as in Lemur. Anterior to the fissure of Sylvius are three small and straight 

 sulci, all placed longitudinally, at different levels, the first on the upper, the second on 

 the outer, the third on the lower (orbital) surface of the hemisphere. The two former 

 may be called " supero-frontal " and " infero-frontal." There is no appearance either 



' The nomenclature proposed by Mr. Huxley (Proc. Zool. Soc. 18C1, p. 2.59), founded on that of M. Gra- 

 tiolet, is used throughout, when speaking of the cerebral sulci and gyri of the Quadrumana. 



