414 PHYSIOLOGICAL SERIES. 



compensatory to the calcarine sulcus, around which they are 

 grouped in such a peculiar manner. 



There is always a well-developed intercalary (calloso- 

 marginal) sulcus with an upturned caudal extremity. And 

 generally there is a small separate rostral sulcus. 



In proportion to the size of the cerebral hemispheres, the 

 other regions of the brain seem very diminutive in the Apes. 

 This is very striking in the case of the quadrigeminal and 

 geniculate bodies, and even more so as regards the corpora 

 mammillaria and interpeduncular body. Even the cere- 

 bellum appears to be very small in the Apes, although its 

 actual size in comparison with that of the body is great. 

 The pons Varolii is relatively broad, but not sufficiently so 

 to hide the trapezoid body, which is in the Cercopitheeidse 

 quite as distinct as it is in the Carnivora. The pyramidal 

 tracts are relatively very large and prominent. And the 

 olivary body is very distinct. 



The cerebellum in the Apes is very different in shape 

 from that of other mammals because it becomes moulded 

 to the configuration of the cerebral hemispheres which 

 overlap it. Structurally it does not differ much from the 

 organ in other mammals. But the relative size of the 

 floccular lobe has become greatly reduced, although not 

 nearly to such a marked extent as it is in 7/omo, Anthropo- 

 pithecus, and Simla. It is noteworthy that the lateral 

 lobule of the floccular lobe, i. e. the paraflocculus, is still 

 larger than the mesial lobe (flocculus) and is provided with 

 a projecting pedunculated appendage tho petrosal lobule 

 as is the case in many lowlier mammals. 0. C. 1338 C^. 



D. 595. The brain of a new-born Bengal Macaque (Macacus 

 rhesus). Tho left hemisphere has been detached. 



The intraparietal sulcus gives off (in each hemisphere) a 

 -liort branch towards the upper margin of the hemisphere* 

 Such a short branch is probably a representative of part, 

 and not of the whole of the ramus postcentralis superior of 

 the intraparietal sulcus, for its direction is not that taken 

 by the isolated subdivision of the latter. Otherwise the 

 specimen presents characters wholly in agreement with 

 those of D. 594. 0. C. 1338 c b. 



