MARSHALL OX THE EIU1X or A VoUXG CHIMPANZEE. 313 



between Ike hinder end of the corpus eallosnm and the internal perpen- 

 dicular fissure. The widths of the cornna of the lateral ventricle vary 

 according as their sides are held asunder, but they are large cavities. 

 About the same proportionate quantities of corpus striatum and optic 

 thalamus are seen in the anterior coram and body of the ventricle, 

 as in man. In fig. 5, the thin curved margin of the fornix, with the 

 rounder commencement of the hippocampus major, are seen entering 

 the descending cornu. On the inner side of the floor of the posterior 

 cornu is a convex eminence, the hippocampus minor. Between the bend 

 of the hippocampus major and the hippocampus minor is a triangular 

 eminence, also prolonged into the posterior cornu ; this is a small pes 

 accessorius or eminentia colJateralis. All the parts to be found in 

 the human posterior cornu are thus represented in the Chimpanzee, 

 m proof of which we may refer to the irrefragable evidence of the 

 photograph, fig. 5. A comparison of the natural parts with Schroe- 

 der van der Kolk's and Yrolik's figure, 4, Plate II., — which is so dif- 

 ferently interpreted just now, being equally quoted* to show the pre- 

 sence and the absence, in the Quadrumanous brain, of the same parts, 

 viz. the posterior lobes, the posterior cornu, and the hippocampus minor, 

 has compelled me to the conclusion that, although those anatomists 

 have had to dissect a displaced and deformed posterior lobe, and have 

 removed its substance rather freely, still the eminence figured, and 

 marked e, by them, is really a Idppocampus minor. To make this clear 

 we may refer to the annexed sketch, fig. A., drawn by myself from 

 nature, in which the parts are shown of their true size. 



Pig. A. 



Fig. A. O, occipital lobe. T, temporo-sphenoidal lobe. Th, back of thalamus 

 opticus. V, internal perpendicular fissure. H, part of fissure of hippocampus, a, 

 hinder part of body of lateral ventricle, b, descending cornu. c, posterior cornu. 

 dd, hippocampus major, e, hippocampus minor. At J) the small eminentia col- 

 lateralis ; both of the latter extend into the posterior cornu. g, fascia dentata. h, 

 continuation of fornix or corpus fimbriatum. 



* By Professor Huxley, in this Journal, p. 76 ; and by Professor Owen, in the 

 recent No. (June 1861) of the Annals and Mag. of Nat, History, p. 456. 



