NERVOUS SYSTEM. VERTEBRATA. 379 



how closely they resemble the corresponding regions in 

 other mammalian Orders. 



The rhinal fissure is very distinct and can be seen cross- 

 ing the vallecula Sylvii to become the posterior rhinal. 

 The latter soon ends near the parallel sulcus, with the 

 lower end of which it appears to become continuous. The 

 Sylvian fissure and the intraparietal sulcus are like those 

 of the Lemur. The upper extremity of the parallel sulcus 

 curves forward so as almost to join the upper end of the 

 Sylvian fissure, as sometimes occurs in the Lemur. 



There is a short arcuate sulcus rectus and, between it 

 and the Sylvian fissure, a sulcus (x) closely resembling the 

 central sulcus o the Anthropoidea. There is no conclusive 

 evidence to enable us to determine the homology of this 

 sulcus, which often makes its appearance in the Lemurs, in 

 Propitliecus (occasionally), and in Daubentonia *. There is 

 a well-marked orbital sulcus. The lower extremity of the 

 fascia dentata is distinctly seen on the base of the brain 

 on each side of the tuber cinereum ; and the projections 

 of the posterior part of the pyriform lobe which Gustav 

 Retzius calls gyrus lunaris and gyrus ambiens are very 

 prominent. The structure which Retzius calls "gyrus 

 lunaris " is not a cortical formation, but is merely the 

 surface of the nucleus amygdalae and ought to be so called. 



0. C. 1337 B. 

 D. 548. The brain of a Javan Slow-Loris (Nycticebu* tardujradus) 



(fig. 221). 



Fig. 221. (Nat. size.) 



SULC.1NT. 



SULC.TR.OCC. 



SULC.RECT 



-"".,.^1-1 . -SULC. FAR. 

 SULC.ORB. 



The brain of Nycticebus is, for a Lemur, unusually rich 

 in sulci, the arrangement of which is peculiar in several 

 respects, and is not symmetrical on the two sides. 



* Since the above was written I have become convinced that the furrow x 

 can be no other than the true sulcus centralis. 



