378 PHYSIOLOGICAL SERIES. 



As Dr. Forsyth Major has clearly and decisively demon- 

 strated," the optic nerves enter the cranium in n situation 

 extraordinarily far forward. The pattern formed by the 

 cerebral sulci, however, closely follows that of the other 

 Lemuridae. 



These peculiar modifications are the result of retrogres- 

 sive changes which occur partly in the ontogeny of every 

 individual, as a result of which the brain becomes actually 

 smaller in the adult than it is in the young animal. 



Forsyth Major, Proc. Roy. Soc. vol. Ixii. 1898, p. 47. 



D. 546. The brain of a Slender Loris (Loris gracilis). 



This brain resembles that of the Lemur. 



The rhinal fissure is distinct in front, but rapidly becomes 

 indistinct on the caudal side of the vallecula Sylvii. 



The usual Lemurine forms of the Sylvian fissure, the 

 intraparietal and the parallel sulci are present. The in- 

 teresting relationship between the upper extremities of the 

 Sylvian fissure and the parallel sulcus, noted in the Lemurs 

 proper, is also found here. 



The mesial surface shows the typical Lemurine features. 



Ziehen, Arch. f. Psych., Bd. xxviii. 1896, p. 908. 



O.C. 1337 A h. 



D. 547. The brain of a Potto (Perodicticus potto) (fig. 220). 



[Although this brain is presumably that described by 

 Ziehen (op. cit. 1896, p. 901), the fig. 3 of his memoir can 



Fig. 220. (Nat. size.) 



SULC. INT. 



: ~> 



SULC. PAR. 



A 7 I --. / J _ JfP9( 



LC. RECT. 



SULC. one. 



hardly be regarded as an accurate representation of this 

 specimen.] 



The excellent preservation ^ tli<> olfactory bulb and its 

 crn-linil append&gefl enables us to appreciate tin- lar^e [for 

 ;i Primate] size of these olfactory region- <>\' tin- I. rain, and 



