MOTOR NUCLEI IN PHYLOGENY 



73 



In Anolis Willard has described in detail the central origin 

 of the motor V root which in this form is arranged on a plan 

 somewhat similar to that obtaining in Varanus. In the former 



Fig. 6 Damonia subtrijuga. Transverse section through the medulla at the 

 exit level of the motor trigeminal root. Abbreviations: Nu. V. m., motor tri- 

 geminal nucleus; Nu. V. s. p., so-called principal sensory trigeminal nucleus in 

 which components from all three divisions of this nerve terminate near the level 

 of their entrance; R. V. to., motor trigeminal root; R. V. mes., emergent mesen- 

 cephalic trigeminal root fibers; R. V. s. md., root fibers of the mandibular divi- 

 sion of the trigeminus which enter the brain stem somewhat caudad of those of 

 the ophthalmic-maxillary division, R. V. s. rm. (V. Valkenburg, I.e.); Tr. VIII., 

 area acustica alba. Other abbreviations as before. 



animal the motor V root is described as arising from two cell 

 groups, one of which is placed a short distance dorsomesiad of 

 the peripheral attachment of the root, while the second occupies 



