NERVOUS SYSTEM. VERTEBRATA. 397 



small sulcus (triradiate on the right side, and on the left 

 linear and prolonged forward into what is obviously a com- 

 pensatory orbital sulcus). This small sulcus is one of the 

 earliest forms of the fronto-orbital sulcus of the Simiida*, 

 which becomes in Man the anterior limiting sulcus of the 

 island of Reil. 



The Sylvian fissure becomes confluent with the simple 

 linear intraparietal sulcus, which ends just behind the 

 parieto-occipital sulcus. 



There is a very short central sulcus, and between it and 

 the intraparietal a small punctate ramus postcentralis 

 superior of the intraparietal. 



The simple parallel sulcus nowhere approaches the Sylvian 

 fissure. 



There is a simple arcuate sulcus rectus running parallel 

 to the fronto-orbital margin. On the right side it gives off 

 a small branch. In front of the mid-point of the central 

 sulcus there is a small depression, which may possibly 

 represent the incipient arcuate sulcus. 



Behind the upper end of the parallel sulcus there is a 

 short transverse occipital sulcus, and behind this a second 

 small furrow (? inferior occipital sulcus). Beginning near 

 the end of the posterior rhinal sulcus there is a deep and 

 well-defined occipito-temporal sulcus on the tentorial 

 surface. 



The cerebellum is of great interest, because it is still 

 sufficiently simple to permit us to recognize the principal 

 features exhibited by the non-Primate organ, and yet the 

 exuberant growth of its lateral parts clearly points to the 

 human homologies of the various regions. 



The most instructive parts of the organ in this specimen, 

 however, are the floccular lobes. For this example clearly 

 shows that this part of the cerebellum is composed in the 

 Apes, as in other mammals, of two distinct parts or lobules 

 a small mesial part (surrounding the auditory nerve) 

 being the flocculus proper, i. e. the part we call by that 

 name in the human brain ; and a large lateral part or para- 

 flocculus, which dwindles to a mere vestige (flocculi 

 secundarii of Henle) in the brain of Man. In this brain 

 the flocculus is a narrow sagittal band of about seven 



