252 



THE RHOMBENCEPHALON. 



inferior cerebellar surface is limited by the horizontal sulcus 

 and is separated from the medulla by the transverse fissure of the 

 cerebellum. It is more complex than the superior surface; and 

 its sulci are more sharply curved forward as they pass from the 

 worm into the hemispheres. 



Sulci of Lower Surface (Fig. 80). The interlobular sulci 

 of this surface are very deep. They are three in number, namely: 



(i) The postnodular sulcus (s. postnodularis] (Figs. 77, 

 79 and 80) is in the anterior end of the worm between the nodule 



Fig. 80. Inferior surface of cerebellum. (Original.} 



a. Pyramid, b. Flocculus, c. Nodule, d. Brachium pontis. e. Restiform body. f. Su- 

 perior medullary velum, g. Brachium conjunctivum. h. Quadrangular lobule, i. Post- 

 nodular sulcus. j. Uvula, k. Tuber' vermis. 1. Ant. and m. Post. Slender lobules, n. In- 

 ferior semilunar lobule, o. Tonsil, p. Biventral lobule, q. Horizontal sulcus. r. Lobulus 

 gracilis. s. Prepyramidal sulcus. t. Postpyramidal sulcus. u. Post, cerebellar notch. 

 v. Sulcus valleculae. 



and uvula. In the hemisphere it winds forward and outward 

 between the inferior medullary velum and the tonsil, and then 

 continues lateralward between flocculus and biventral lobule 

 to the horizontal sulcus. It is the first cerebellar sulcus to be 

 developed (Cunningham). 



(2) The prepyramidal sulcus (s. prapyramidalis} (Figs. 79 

 and 80), situated between the uvula and pyramid, is very con- 



