SUMMARY' OF STRUCTURES 463 



greater degree of differentiation in tlie upper extremity and hand. This inter- 

 pretation gains in prolDabiHty because in the baboon the fore extremity, 

 particularly tlie hand, is inihienced in its differentiation by adaptation to loco- 

 motion upon the ground, while in the gibbon the hand and upper extremity 

 are pecuharly adapted to arboreal locomotion. In macacus, however, there is 

 some degree of freedom of the hand which approaches more nearly the 

 humanoid standard ot a forelimb. Not in size alone, but quite as much in the 

 specialization of the accessory nucleus of Blumenau, the nucleus of Burdach 

 shows a greater degree of differentiation in macacus than in gibbon or baboon. 

 The planimetric coeflicients of the nucleus of Burdach (including the acces- 

 sory nucleus of Blumenau) in baboon, macacus and gibbon are shown in the 

 appended tabulations : 



Coefficients of the Nucleus of Burdach in the Intermediate Primates 



The longitudinal coefficients of the two dorsal groups of sensory nuclei 

 are also given. From the latter tabulation, it is of interest to note the 

 general consistency in length of both the nucleus of Goll and of Burdach. 

 The only notable departure from this equality is the length of the nucleus of 

 Goll in gibbon which is practically half that of the other forms. This fact 

 accords with the observations already made on the basis of the planimetric 

 coefficients of this nucleus in gibbon. 



As compared with the nucleus of Burdach in the lower primates, the 

 planimetric figures show that in mycetes this nucleus is larger than in all 

 other forms cither of the lower or the intermediate groups. This pre- 

 dominance of mycetes in both of its dorsal nuclear specializations must be 



