NERVOUS SYSTEM. VERTEBRATA. 341 



D. 487. A cast of the cranial cavity of a Sheep (Ovis aries). 



D. 488. The left half of the brain of a Sheep (Ovis aries), sepa- 

 rated by a mesial sagittal section. 



The Sylvian depressed area is very well shown. 



O.C. 1327 A b. 



D. 489. The right half of the brain of a Sheep (Ovis aries). 



The typical arrangement of sulci is well demonstrated. 



The paraorbitai sulcus, which is merely the upturned 

 anterior extremity of the anterior ectosylvian sulcus, is 

 joined to the true orbital sulcus. 



The posterior ectosylvian sulcus is joined to the rhinal 

 fissure by an accessory sulcus, which completes the caudal 

 boundary of the Sylvian trigone and probably represents the 

 pseudosylvian fissure of the Carnivora. 0. C. 1327 A c. 



D. 490. The brain of a Sheep (Ovis aries), in which the lateral 

 ventricles have been opened and the corpora striata and 

 hippocampi exposed. 0. C. 1327 A a. 



D. 491. The brain of a Sheep (Ovis aries), in which a great part 

 of the cerebral hemispheres has been removed so as to 

 expose the corpora striata, optic thalami, pineal body, 

 corpora quadrigemina, and cerebellum. 



The great extent of the anterior quadrigeminal bodies is 

 shown. 



The characteristic features of the typically Ungulate 

 cerebellum the narrowness and the simple transverse 

 arrangement of the folia on the lateral parts of the organ 

 are clearly seen. The floccular lobes are exceedingly 

 large and complicated ; they form cake-like masses applied 

 to the lateral aspect of the truncated lateral regions of the 

 " middle lobe " of the cerebellum. 



The flocculus (sensu stricto) is a little feather-like structure 

 placed on the middle peduncle below the great irregular 

 paraflocculus. 0. C. 1327 A. 



D. 492. The right half of the brain of a Sheep (Ovis aries). 



The orbital (presylvian) sulcus is quite independent of 

 the anterior ectosylvian sulcus. 0. C. 1327 A e. 



