THE NERVOUS SYSTEM. 



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running from the aqueduct of Sylvius and the upper surface of the cerebral 

 protuberance to the upper surface of the spinal chord, and united to, 29. the 

 cavity commonly called calamus scriptorius. 30. Upper extremity of the spinal 



seen on the upper part of the ethmoid bone, before the cor- 

 pora albicantia. (Cut, p. 304?.) From the posterior part of the 

 third ventricle a canal, called aquceductus Sylvii, or iter a tertio 

 ad quartum ventriculum, runs back, under the base of the corpora 

 quadrigemina, into a cavity in the cerebellum called the fourth 

 ventricle. 



On cutting the Cerebellum, which has two lobes united by a 

 projecting portion called vermiform process at the superior-ante- 

 rior and superior-middle part, we find it less consistent than the 

 other parts of the encephalon. Its fibrous substance within is 

 collected into three masses; two lateral, and sending offprolong- 



1. Continuation of the central fissure of the spinal chord. 2. Beginning of 

 the anterior pyramids. 3,3. Anterior pyramids. 4, 4. Corpora olivaria. 5, 5. Cor- 

 pora restiformia. 6, 6. Cross band uniting the corpora olivaria. 7. Horizontal 



