i8o THE LOWER PRIMATES 



LEVEL OF THE OPTIC CHLA.SM (FIG. 89) 



At the level of the optic chiasm the identifying feature is the decussation 

 in the optic pathway (Opt). The optic thalamus is also represented. This is 



FIG. 89. MARMOSET. LE\EL OF THE OPTIC CHIASM. 



CIN, Internal Capsule; cph, Corpus Hypotlialamicum; fdp, Descending Pillars of the Fornix; glb, Globus 

 Pallidus; hab. Nucleus Habenulae; mf. Mesial Fillet; nmt, Medial Nucleus of the Thalamus; nli, Internal 

 Lateral Nucleus of the Thalamus; nlt, External Lateral Nucleus of the Thalamus; opt. Optic Tract; OPX, 

 Optic Chiasm. [Accession No. 146. Section 219. Actual Size 19 X 12 mm.] 



an important structure inasmuch as it represents the last great relay station 

 for the conduction of all types of sensibility with the exception of the olfac- 

 tory sense. Situated ventral to the main nuclei of the optic thalamus is a 

 diffuse collection of fibers and gray matter, the corpus hypothalamicum 



