CALLITHRIX JACCHUS, THE MARMOSET 



165 



nerve (Trd). This dorsal field of sensory discrimination, embracing the 

 three major sensory territories of the body, the head and face, neck and 

 upper extremity, leg and tail, is almost as conspicuous as m lemur. Its pro- 



FIG. 79. MARMOSET. LEVEL OF THE PYRAMIDAL DECUSSATION. 



CEN, Central Gray Matter; CB, Column of Burdach; CG, Column of Goll; dt, Deiterso-spinal Tract; fle. 

 Dorsal Spinocerebellar Tract; cow, Ventral Spinocerebellar Tract; hel, Spino-olivary Tract of Helvveg; 

 NB, Nucleus of Burdach; NC, Nucleus of Goll, nr. Nucleus of Rolando; pv, Pyramid; pvx, Pyramidal Decus- 

 sation; TRD, Descending Trigeminal Tract; ven, Ventral Gray Matter; xpv. Crossed Pyramidal Tract. 

 [Accession No. 146. Section 4. Actual Size 5X3 mm.] 



portional development of gray matter, as well as the size of the tracts, has 

 practically the same connotation as in the lower form already described. 

 Thus, sensory conduction from the leg and tail, head and face is less amply 

 represented than that from the arm and neck. The significance of this rela- 

 tive disproportion is obvious at a glance. The head, forearm and the hand are 



