THE CEREBELLUM. 



243 



two inches from before backward and about the same in thick- 

 ness, antero-medially ; but they taper rapidly toward the lateral 

 borders (Figs. 76 and 77). They-are joined together by the worm, 

 or vermis, which forms the central and most elevated part of .the 

 cerebellum. 

 The vermis cerebelli, or worm, is a small elongated lobe, 



Fig. 76. Dorsal view of inter-brain, mid-brain and cerebellum. Superior surface 

 of cerebellum. (Original.) 



a. Pineal body. b. Colliculus superior of corp. quad. c. Lateral sulcus. d. Colliculus 

 inferior of corp. quad. e. Culmen monticuli. f. Pars posterior of quadrangular lobule, 

 g. Superior semilunar lobule, h. Anterior tubercle of thalamus. i. Stria medullaris thalami. 

 j. TrigonunvhabenulEe. k. Mid-brain. 1. Inferior horn of lateral ventricle, m. Pars an- 

 terior of quadrangular lobule, n. Predeclivil sulcus. O. Postdeclivil sulcus. p. Declive 

 monticuli. q. , Folium vermis. r. Posterior cerebellar notch, s. Horizontal sulcus. 



shorter and much thinner than the hemisphere (Figs. 76 and 80). 

 In animals lower than mammals, it is not differentiated from the 

 hemispheres and appears to be the only part of the cerebellum 

 present, being very large in birds and swimming reptiles (Edinger). 

 Its transverse ridges give it a worm-like appearance. It unites 

 the upper half of the medial aspect of the two hemispheres, their 



