86 AYES. 



of the cerebellum; in its having convolutions; in the thickness of the parietes of 

 its small cavity, which communicates with the other ventricles. In the absence of 

 longitudinal eminences extending towards the calamus scriptorius, and forming the 

 ventricular cord; in the greater thickness of the oblong medulla. It agrees in the 

 presence of the anterior, posterior, and soft commissures ; in crura extending to the 

 oblong medulla, and in the similar arrangement and origin of the nerves. 



It differs from that of many of the mammalia in the want of convolutions and the 

 corpus callosum, or great commissure. In the great thinness of the posterior parietes 

 of the lateral ventricles ; in the radiated form of the septum, and the different con- 

 struction of the floor of this cavity ; in its being continuous with the sides of the 

 ventricles, and not separate like the fornix. In the hollow optic lobes instead of the 

 quadrigeminal bodies. It agrees in having small lateral lobes, similar to the lobules 

 attached to the sides of the cerebellum in the monkey and some other animals, and 

 also in their being placed in a hollow, partly surrounded by a semi-circular canal, 

 which in man, and some animals, is occupied by part of the petrous portion of bone. 

 It differs in the continuation of the third ventricle into the cerebellum as well as into 

 the calamus scriptorius ; in the want of the annular tubercle, although there is a 

 considerable enlargement of the oblong medulla at this part. 



The spinal cord in the neck is frequently thin and narrow for allowing extensive 

 motion, but is thicker and broader at the parts from which the larger nerves arise ; 

 it is more prominent on each side at the origin of every nerve, and thus slightly 

 resembles the unequal cord of some invertebrate animals ; but it is in shape only, 

 and not from the presence of ganglia. It is continued to the tail. It has a distinct 

 ventricle at the loins, which is shut only by membrane ; it is closely surrounded by a 

 thin plate of bone at the immoveable vertebrae of the back ; at the same parts each 

 anterior and posterior bundle of nerves is similarly incased. The width of the canal 

 of the moveable vertebras shows that the space exists entirely for the free accommo- 

 dation of the cord in flexion. 



In the nerves there is very little difference from those of several of the amphibia. 

 The olfactory is not so coarse ; the glosso-pharyngeal is rather larger in proportion to 



