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surface of the posterior lobe of all apes) is not only very deep, but 

 has concealed within it a convolution of considerable size, in the form 

 of a longitudinal eminence attached to the floor of the fissure. The 

 eminentia collaterals is prominent. The hippocampus major is 

 smooth upon the surface. The anterior cornu is of the same form 

 and extent as in the human brain. 



In the brains of C. sabceus, C. mona, and C. ruber a similar dis- 

 position of these parts was found, In the last named, the posterior 

 lobe of the cerebrum is even more prominent, and the hippocampus 

 minor of still greater size, as it tapers less towards its termination ; 

 in fact this eminence is here actually larger than the hippocampus 

 major, to which its true relation can be better studied in these apes 

 than in man. 



Macacus, In a monkey of this genus (M. erythrceus) the pos- 

 terior cornu and hippocampus minor were observed to obtain almost 

 as large a development. 



Family 2. PLATYRRHINA. 



In Cebus apella, the ventricular cavity resembles in all essential 

 particulars that of Cercopithecus. There is the same extent of pos- 

 terior cornu and the same complex arrangement of anfractuosities, 

 producing the very protuberant hippocampus minor. 



It is among the members of this family (e. g. Saimiris) that the 

 projection backwards of the posterior lobes of the cerebrum attains 

 its greatest extent. 



Family 3. STREPSIRHINA. 



The cerebral anatomy of the Lemurs is fXill imperfectly known ; 

 therefore a detailed description is given in the paper of the brain of a 

 species of Galago, the most important part of which is the following 

 note upon its internal structure : " A horizontal section of both 

 hemispheres was made at the level of the corpus callosum, and the 

 lateral ventricles laid open. A broad and very distinct posterior 

 cornu extends backwards almost to the extremity of the hemisphere, 

 occupying nearly the whole of the posterior lobe. Its floor and inner 

 wall are raised into a prominence, having distinctly the characters 

 of the hippocampus minor as found in man and the higher Quadru- 

 mana, and corresponding with the bottom of the sulcus before noted 

 on the under surface of the lobe. The form of this eminence is some- 

 what triangular, the apex being directed backwards ; but the surface 



