INFERIOR SURFACE OF THE CEREBELLUM. 



2 55 



one strong lamina of the arbor vitae, which divides into two 

 near the surface. It forms the most prominent lobule of the 

 inferior worm. A low connecting ridge joins the pyramid to the 

 biventral lobule in the hemisphere. The biventral lobule (lobu- 

 lus biventer) is triangular in outline. Its base looks toward the 

 flocculus and is bounded by the postnodular and the horizontal 

 sulcus; its apex is continuous with the connecting ridge joining 



Fig. 81. Sagittal section of cerebellum, cutting nucleus dentatus. (Original.) 



a. Sup. semilunar lobule, b. Corpus medullare. c. Post, part quadrangular lobule, d. 

 Nucleus dentatus. e. Ant. part of quadrangular lobule, f. Interior of dentate nuc. g. 

 Central sulci. h. Brachium pontis. i. Restiform body. j. Inf. semilunar and slender 

 lobules, k. Hilus of nuc. dent. 1. Biventral lobule. 



it to the pyramid. The gyri composing it radiate from the apex 

 toward the base, and are divided into two groups by a very deep 

 intralobular sulcus. Its lateral extension is a little beyond the 

 flocculus. The postpyramidal sulcus bounds it postero-exter- 

 nally, and separates it from the slender lobule. 



Tuber Vermis, Slender and Inferior Semilunar Lobules, 

 Lobus Tuberis (Figs. 79 and 80). The tuber vermis forms the 

 posterior end of the inferior worm. It resembles the lobules of 

 the vermis superior, because some of its half dozen tertiary gyri 



