MYCETES SENICULUS 



209 



surface presents a ventromesial sulcus which is interrupted at its caudal 

 extremity by the decussating pyramidal fibers. Upon either side of this 

 sulcus are two well-defined pyramids indicating an animal having a wider 



FIG. I 16. DORSAL SURFACE OF BRAIN STEM, MYCETES SENICULUS. 

 [Actual Length, 34 mm.] 



Key to Diagram, d. m. fis., Dorsomedian Fissure; d.m.s., Dorsomedian Sulcus; inf. colliculus. 

 Inferior Colliculus; sup. cerebl. peduncle, Superior Cerebellar Peduncle; sup. collicul., Superior 

 Colliculus; TUB. tr., Tuberculum Trigemini. 



range of volitional control than is true of either lemur or marmoset. Lateral 

 to each pyramid is a small ohvary eminence. 



The dorsal surface is characterized by the presence of the two enlarge- 

 ments representing the cohmms of GoII and Burdach. While both of these 

 structures are prominent, the column of Goll is slightly larger than the 

 column of Burdach. The increment in the column of Goll reflects the appear- 

 ance of a highly developed prehensile tail which adds what some authorities 



