CALLITHRIX JACCHUS, THE MARMOSET 



163 



THE CEREBELLUM, THE FOURTH \ ENTRICLE AND THE NHDBRAIN 



The cerebellum is small, presenting a large median portion, the vermis, 

 and two limited lateral expansions, the lateral hemispheres. The size of the 



fig. 78. dorsal surface of brain stem, callithrix jacchus 

 (marmoset). 



[Actual Length, 22 mm.] 

 Key to Diagram, d. m. fis., Dorsomedian Fissure; d. m. sept., Dorsomedian Septum; inf. coll., Inferior 

 Colliculus; SUP. cer. ped., Superior Cerebellar Peduncle; sup. coll., Superior Colliculus; tub. trigem., 

 Tuberoulum Trigemini; 4TH \ ent., 4th Ventricle. 



cerebellum, particularly of its lateral lobe, indicates a coordinating organ 

 with a low degree of functional capacity. From this it may be inferred that 

 the animal's attainment in complex voluntary movements is extremely 

 limited. On removal of the cerebellum the fourth ventricle is revealed, 

 bounded upon either side in its inferior triangle by an inconspicuous clava 

 and in its superior triangle by the superior and middle cerebellar peduncles. 



