66 



THE LOWER PRIMATES 



consummating its progress as it sought new sensory liclds for lurther expan- 

 sion, the functions related to sensibility have attained their fullest representa- 

 tion in the pallium of the cerebral hemispheres. This stepping-up process 



FIG. 33. LEMUR MONGOZ. LEVEL OF THE SUPERIOR COLLICULUS. 



CEN, Central Gray Matter; cp. Cerebral Peduncle; ctt, Central Tegmental Tract; mgb, Mesial Geniculate 

 Body; mf, Mesial Fillet; noc. Nucleus Oculomotorius; nru, Nucleus Ruber; pd, Predorsal Bundle; pl, 

 Posterior Longitudinal Fasciculus; ref, Reticular Formation; sbn, Substantia Nigra; sc, Superior Colliculus. 

 [Accession No. 147. Section 300. Actual Size, 19X9 mm.] 



from a lower, less highly organized region to a higher and more expansible 

 territory in the end-brain, is spoken of as telencephalization. Yet in no case 

 has this transference upward been made at one such stride that the entire 

 allegiance of a certain form of sensibility is advanced from its more lowly 

 sphere of structural organization to its new domain in a higher region. The 

 gradual projection from lower to higher centers is clearly demonstrated in the 

 phyletic series of the vertebrates. Nowhere is there a more marked instance 



