730 



OF THE FUNCTIONS OF THE NERVOUS SYSTEM. 



Thus, of all classes of Vertebrata, Reptiles are the most inert ; and their motions 

 require the least co-ordination. The active predaceous Sharks far surpass them 

 in this respect, and may be compared with Birds, in the energy of their passage 

 through the water, and in their facility of changing their direction during the 

 most rapid progression; their Cerebellum, accordingly, bears to their Spinal 

 Cord very much the same proportion as it does in Birds. On the other hand, 

 the Flat Fish, which lie near the bottom of the ocean, and which have a much 

 less variety of movement, have a very much smaller Cerebellum; and the 

 Vermiform Fishes, which are almost all completely destitute of fins, and whose 



Fig. 194. 



Analytical diagram of the Encephalon in a vertical section. (After Mayo.) s. Spinal Cord. r. Restiform 

 bodies passing to c, the cerebellum, d. Corpus dentatum of the cerebellum, o. Olivary body. /. Column? 

 continuous with the olivary bodies and central part of the medulla oblongata, and ascending to the tubercula 

 quadrigemina and optic thalami. p. Anterior pyramids, v. Pons Varolii. n, b. Tubercula quadrigemina. 

 g. Geniculate body of the optic thalamus. t. Processus cerebelli ad testes. a. Anterior lobe of the brain. 

 g. Posterior lobe of the brain. 



motions resemble those of the lower Articulata, have a Cerebellum so small as 

 to be scarcely discoverable. On looking at the class of Birds, we observe that 

 the active predaceous Falcons, and the swift-winged Swallows (the perfect control 

 possessed by which over their complicated movements must have been observed 

 by every one), have a Cerebellum much larger in proportion than that of the 



