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Show 98 ON CLASSIF !CATION. " In roan the brain presents an asc nRiv st p in clovelopInent, hirrher and n1ore strongly 1narkod than that by which the precedin~ snb-clas wa di t~nguished fron1 th one below it. Not only do the cerebral h 1111sph res overlap tho olfactory lobes and cerebellum, but th y ext n<l in advance of tho one and further back than tho other. Their po terior d velopn1ont is so marked, that anatomi ts hav as igncd to that part the charaeter of a third lobe ; it is poeuliar to tho o· nus IIomo, an(l equally peculiar is the 'po teri r horn of the lat ral v utricle,' and tho 'hippocampus minor,' whi h charact rises th hind lobe of each hemisphere."-L. c., pp. 19, 20. rrhese are the ass rtion. which have b en r p atod over and over again during the la t £ w y ar ; but tlmnk. to tho exertions of the able Con ernttor of your l\In"'rnm, it iR in my power to Jay before you visibl and tangibl fact , whieh prove these assertions to b wholly d void of foundation. The third lobe, eharacteri ed by xt nding further back than the cerebellum, i said to be "pec1.diar to the genus IIomo." I place before you C'a ts f the cranial cavity, aC'curatcly re-presenting the rolativ I o ·iti n of th part of the brain of a ~or ill a, of a Cbilnpanz , f an Orano·, f a Cynocephal1ts; and you ob. erve that the p terior, or third lobe, of each projects further back than th cer b llum in ju 't tho same sonso as a. man's can b aid to do so; an l in 0111 ca. s, as in tho baboon, to a much gr at r xt nt. The a"serti n the t th"' third 1 b , a d fined by Professor Owen, i "peculiar t 111an," i ther for d 1non trab1y contrary to fact. "Equally peculia?· is the posteriot· hm~n of the lateral ventricle." Side by sid upon th table ar two di rctions, made in the same way, the on f the brain fan Orang-utan, tho other tha.t of a 1 an, taken at hazard Ly l\'Ir. Flow r, who has been good enough to dis ect both (Fig. 40). Every one in thi theatr , I imagine, can see perfectly well that the Orang has a post ri r corm1, which, in proportion to the size of its brain, i just as long and nearly as much incurved THE THIRD LOBE AND POSTERIOR CORNU. 99 as that of the man, while it is a good deal wider at its commencement. Fig. 40. 2 Fig. 40.-Figures [reduced to the sa 1 J Orang which were exhibit d . ~~ sc~ e of the dissected brains of a Man and of an anterior cornu . n2 desced . m e t leatre of the Royal College of Surgeons -(Jl h ' hi•p pocampus, mvi,n or. en mg cornu·' ca ' post eu.·O I. co.i nu; L."~r., hI' ppocampus m' ajor;' H 2 |