LEMUR MONGOZ 69 



mcnts of a primordial character largely vested in the midbrain. Immediately 

 dorsal to the substantia nigra is the mesial fillet (Mi), while occupying 

 positions in front of the oculomotor nuclei are two decussations. One of 



FIG. 34. LEMUR MONGOZ. LEVEL OF THE OPTIC CHIASM. 



CIN, Internal Capsule; cph. Corpus Hypothalamicum; fdp. Descending Pillar of Fornix; gh. Ganglion 

 Habenulae; glp. Globus Pallidus; mf, Mesial Fillet; nl, Nucleus Lateralis Thalami; nm, Nucleus Mcdialis 

 Thalami; opt, Optic tract; OPX, Optic Chiasm. [Accession No. 147. Section 363. Actual Size, 25 X 15 mm.] 



these is the dorsal decussation of Mcjnert through which the emer- 

 gent fibers of the third nerve make their way toward the surface. Ventral to 

 the dorsal decussation of Meynert is the smaller decussation of Forel. 

 These decussations represent respectively the crossing of the fibers arising in 

 the reticular formation of the midbrain to enter into the predorsal bundle 

 (PD) and the decussating descending fibers arising in the red nucleus to 

 form the rubrospinal tract. 



