RECONSTRUCTION OF CALLITHRIX JACCHUS 



189 



tion is lound the discrete nucleus described in connection with lemur, from 

 which nerve fibers pass dorsomesially into the mesencephalic tegmentum. 

 Its cephalic termination is uncertain as it seems to attenuate and disappear 



FIG. 93. LATERAL SURFACE OF THE GRAY MATTER OF THE BRAIN STEM, 



CALLITHRIX JACCHUS. 

 Key to Diagram, dors, cochl.. Dorsal Cochlear Nucleus; inf. olive, Inferior Olive; nucl. of burdach, 

 Nucleus of Burdach; nucl. of deiters, Nucleus of Deiters; pontile, Pontile Nuclei; ret. form.. Reticular 

 Formation; subst. gel. rolando. Substantia Gelatinosa of Rolando; sup. coll., Superior Colliculus; 

 VENT. COCHL., Ventral Cochlear Nucleus. 



with no continuity with the thahimic structures, although it appears to be 

 rephiced by the zona incerta of the diencephalon. 



The Colliculi 



In the reconstruction, the inferior collicuhis arises at the lower mes- 

 encephahc level from the reticular formation laterally and the tectal gray 

 matter surrounding the upper extremity of the fourth ventricle mesially. It is 

 separated from the superior cerebeHar peduncle by a narrow lateral prolonga- 

 tion from the reticular formation of the mesencephalic tegmentum. Mesially 



