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so great an extent as in the human brain. To examine the interior, 

 the right hemisphere was removed to the level of the inferior surface 

 of the corpus callosum, and then further portions were carefully 

 dissected away, so as to expose the lateral ventricle, with its three 

 cornua and their contained structures. It is to be observed that 

 brains which have been long in spirit are in some respects not so 

 well adapted for dissection as when in a recent condition, as the 

 distinction in appearance between the white and grey substance is 

 lost, and the contiguous walls of cavities, which in the natural state 

 would have fallen apart, have now become hardened in such close 

 contact, that their real nature may readily be overlooked. In this 

 way only can the statements of Tiedemann as to the absence or 

 rudimentary condition of the posterior cornu in the Simiae be 

 accounted for. However, the brain of this Orang is sufficiently well 

 preserved to show that its ventricular cavity presents almost the 

 exact counterpart of that in the human subject. The posterior 

 cornu extends quite as far backwards as in an average example 

 in man, its apex being but of an inch (=^ of the entire length 

 of the hemisphere) from the occipital extremity of the hemi- 

 sphere ; and its direction well answers to the description " back- 

 wards, outwards, and then inwards." Upon the inner wall of the 

 cavity is the hippocampus minor, which will bear comparison with 

 a very well- developed specimen of this structure as met with in the 

 human brain, where, as is well known, it is subject to great variations 

 in size and form. Its length is f inch, its breadth at the base ^ 

 inch. The portion of the wall of the ventricle situated oppo- 

 site the junction of the descending and posterior cornua (called 

 eminentia collateralis or pes accessorius) corresponds in configura- 

 tion and relative size to the similar part in the brain of man. The 

 hippocampus major has no distinct digital marks ; these are, how- 

 ever, indicated by a nodulated appearance in the expanded termina- 

 tion. The remaining portion of the ventricle presented nothing 

 requiring special remark. In order to verify these observations by 

 an examination of the corresponding parts of the opposite side, the 

 upper part of the left hemisphere was also removed, and a very 

 good view obtained of the ventricle, with its posterior cornu. It was 

 precisely similar to that just described, the two sides exhibiting in 

 their internal structure a perfectly symmetrical appearance. 

 VOL. xi. 2 E 



