434 PHYSIOLOGICAL SERI1 



arch around the bifid Sylvian, such as sometimes happen- 

 in the Baboons. 



There is a very long and complete linear collateral 

 sulcus. The calcarine sulcus is parallel to the parieto- 

 occipital, and the two are separated throughout by an 

 exposed gyms. 



The inferior occipital sulcus is very small, but the 

 posterior element of the occipito-temporal sulcus is deepened 

 and lengthened in compensation, and ends posteriorly in a 

 horizontal sulcus below and parallel to the typical Y-^hapcd 

 lateral occipital sulcus. On the left hemisphere there is a 

 shallow compensatory sulcus both above and below the 

 latter. 



The anterior separate portion of the occipito-temporal 

 sulcus is parallel to the anterior half of the collateral, and 

 is deepened at the expense of the inferior (middle) temporal 

 sulcus, the anterior portion of which consequently dis- 

 appears on the left side. The posterior part of the inferior 

 (middle) temporal sulcus is prolonged on to the tentorial 

 surface between the anterior part of the occipito-temporal 

 and inferior occipital sulci. On the mesial surface there 

 are typical calloso-marginal and rostral sulci. 



The whole of the ventral surface of the brain-stem 

 closely resembles that of a very small human brain. The 

 optic and auditory nerves are, however, proportionately 

 much larger than in Man. A very small area of the 

 trapezium seems to be exposed just to the outer side of the 

 sixth nerve. 



The floccular lobe presents a very marked contrast to 

 that of the Gibbon and all the Cercopithecidou and Cel)id;e. 

 It is relatively very much smaller, and the shrinkage 

 affects almost wholly the paraflocculus, which becomes 

 reduced to very small proportions, so that none of its folia 

 project to form a " pet.rosal lobule." In this specimen the 

 paraflocculus is even so reduced as to be completely hidden 

 under the flocculus, like the flocculi secundarii of Henle in 

 the human brain. 



The enormous lateral expansion of the main mass of the 

 cerebellum has resulted in the formation of an organ 

 exactly like a small human cerebellum. 



0. C. 1338Ha*<fcHa. 



