SUMMARY OF STRUCTURES 



263 



has been noted. The following tables give the planinietrie and longitudinal 

 coefficients of Deiters' and Schwalbe's nuclei in lemur, tarsier, marmoset and 

 mycetes : 



Pla.nimetric Coefficients of the Vestibular Nuclei in 

 Lemur, Tarsier, Marmoset and Mycetes 



Such ditlerences as do exist in the vc^stibular nuclei of these specit^s 

 appear to favor tarsius, a fact which denotes how much more this animal 

 depends upon its balancing function than lemur, mycetes or marmoset. 

 This added functional responsibility may be inherent in tarsius due to its 

 locomotion. In mycetes the problem in balancing includes not only the 

 ordinary locomotion of climbing, leaping and swinging by hands and feet, 

 but also embraces the many postures oi the body incident to suspension by 

 means of the tail. Mycetes is capable of assuming positions in which the body 

 is suspended while the hands and feet are freed for other activities than those 

 of locomotion. In such positions as these the requirements of balance must 

 be considerably greater than in other primates. The entire process of motor 



