NERVOUS SYSTEM. VERTEBRATA. 403 



D. 579. The brain of a Brown Capuchin ( Cebus fatuellus) . 



The small simple Simian sulcus is separated from the 

 transverse occipital ramus of the intraparietal by a broad 

 exposed gyms. 



The ramus postcentralis superior of the intraparietal 

 sulcus is wanting. 0. C. 1337 K d. 



D. 580. The brain of a Brown Capuchin (Cebus fatuellus) . 



This specimen, on the other hand, closely resembles the 

 two brains of C. lunatus, especially in regard to the 

 Affenspalte. 0. C. 1337 K^. 



D. 581. The brain of a Brown Capuchin (Cebus fatuellus) . 



0. C. 1337 K h. 



D. 582. The brain of a White-throated Capuchin (Celus hypo- 

 leucus) . 



This brain resembles that of Cebus albifrons so far as the 

 Affenspalte is concerned. 0. C. 1337 K&. 



D. 583. The brain of a White-throated Capuchin (Cebus hypo- 

 leucus), (<?). 



This resembles the preceding specimen. 0. C. 1337 K b. 



D. 584. The brain of a Smooth-headed Capuchin (Cebus 

 monaclius). The left hemisphere has been separated. 



In this large series of Cebus-brains the features are 

 so constant that the only variation specially noted above 

 has been the somewhat trivial point whether or not 

 the posterior lip of the Simian sulcus extends forward 

 sufficiently far to give the appearance of a fusion of the 

 intraparietal and Simian sulci. On the right hemisphere 

 of this specimen, the opercular lip of the Simian sulcus 

 almost (but not quite) reaches the anterior lip of the ramus 

 occipitalis transversus, whereas they are more widely 

 separated on the left hemisphere. This brain therefore 

 exhibits two interesting stages intermediate between the 

 condition of the Affenspalte-region in the extreme types 

 exhibited by Cebus lunatus (D. 575) and C. hypoJeucus 

 (D. 582) (D. J. Cunningham, Mem. -Roy. Irish Acad. 

 1892, p. 222). 



Note on the right hemisphere two faint depressions 

 representing a superior frontal sulcus. 0. C. 1337 K t . 



2D2 



