314 OEIGINAL ARTICLES. 



The hippocampus minor, as in man, corresponds, on the surface 

 of the Chimpanzee's brain, with the upper of the two deep hidden 

 sulci at the bottom of the fissure of the hippocampus ; and the emi- 

 nentia collateralis with the lower of those sulci. Hence, as already 

 deduced from other considerations, even the presence of this fissure, 

 without its sulci and the corresponding projections into a posterior 

 cornu, would suffice to identify corresponding parts of the cerebral 

 hemisphere. The remaining points, which seem worthy of notice, 

 are the following. The hippocampus major corresponded to a thick 

 rolled convolution and sulcus ; its lower end, fig. A, d' was much ex- 

 panded, and, what I shall call, to avoid confusion, its convex border 

 was twice, though feebly, indented. The fascia dentata was quite 

 distinct. Of the corpora quadrigemina, the upper pair were the 

 larger, but the less prominent. The pineal body was large, soft, and 

 contained no gritty particles. The habenuhe were distinct. The 

 pituitary body was large, and wider than deep. The corpora albi- 

 cantia were beautifully seen, quite distinct from each other, and 

 connected, as in man, with the anterior pillars of the fornix. On the 

 medulla oblongata, the corpora olivaria were neatly defined and of 

 good size ; and the decussation of the pyramids was very prettily 

 seen. In some of these points Macartney's description is not quite 

 correct. 



Lastly, all the parts of the cerebellum, so far as I have yet ex- 

 amined them, are the same as in the human encephalon ; only the 

 lateral hemispheres are wider and flatter. I have still preserved this 

 and also the left half of the brain, on which I propose some day 

 to follow the arrangement of the fibres. 



I may be permitted to add, in conclusion, that my sole object in 

 this paper has been to record the results of an anatomical investigation. 

 I have no theory, zoological, or physiological, to support ; I have no 

 leaning towards any of the developmental hypotheses of the origin of 

 species. But, on the question of facts, and the interpretation of those 

 facts, my results, as to the existence of a posterior lobe, of a posterior 

 cornu, and of a hippocampus minor, in the Chimpanzee, will be found 

 to harmonize with the investigations and conclusions of Prof. Huxley 

 and of Prof. Allen Thomson, already published in this Review. 



Description of the Figures in Plate VI. 



N.B. — Nearly all the figures are, as nearly as may be, two-thirds the linear 

 dimensions of the objects. 



Tig. 1. Under view of a plaster cast of the interior of the Chimpanzee's skull, 

 taken before the membranes were removed from the base; (from a photograph.) 

 F F, frontal lobes of the cerebrum; T T, temporo-sphenoidal lobes; O, occipital 

 lobes; V, pons Varolii; M, medulla oblongate; C C, cerebellum. 



Fig. 2. Under view, or base of the Chimpanzee's brain, hardened in spirit, Avith 

 the pia mater and arachnoid taken away. Intended to show the displacement of 

 the parts, especially of the cerebellum, from their natural positions; (from a photo- 





