84 DAVIDSON BLACK 



of the dorsal mandibular moiety of the radix descendens trigemini 

 is primarily determined through the influence of the terminal 

 gustatory area. Thus in reptiles for the first time in phylogeny 

 the reflex action of the musculature of the tongue may be initiated 

 by impulses arising simultaneously in the lingual mucosa and 

 reaching the medulla by way of both trigeminal and gustatory 

 paths. The rostral position of the hypoglossal nucleus of reptiles 

 is an expression of this important reflex influence in accordance 

 with the first concept of neurobiotaxis (Kappers, 32). 



2. Visceral motor nuclei 



V ago-accessor ins complex. In the foregoing description atten- 

 tion has been directed to the fact that the motor vagus column 

 extends well into the cervical region as a small but definite nucleus 

 in Damonia, Chelone, Alligator, and Varanus. In contrast to 

 this, the motor vagus column terminates abruptly in the lower 

 region of the medulla in Boa constrictor. 



Fiirbringer (16) has described the superficial origin, course, 

 and distribution of the nervus accessorius (ramus accessorius 

 X) in Chelonia. In these forms this nerve is somewhat variable 

 in size and innervates the m. capiti-plastralis in common with 

 the third and fourth cervical nerves. In Crocodilia Fiirbringer 

 (17) has also described a nerve homologous with the R. acces- 

 sorius X of chelonians which was distributed to a small part of 

 the m. sterno-mastoideus (viz., m. atlanti-mastoideus) . In the 

 Crocodilia this nerve by reason of its intimate connection with 

 the cervical nerves shows a form and arrangement differing 

 somewhat from that obtaining in chelonians. The superficial 

 origin and course of the nervus accessorius in Varanus has been 

 described by Watkinson (42, p. 467). The nerve in question 

 was found to innervate the 'm. sterno-cleido-hyoideus' ( = m. 

 capiti-cleido-episternalis of Fiirbringer, 17) in common with 

 fibers derived from the third cervical nerve. 



Among the snakes, on the other hand, Hoffmann (26) long 

 ago pointed out that in correspondence with other specializations 

 attendant on the loss of their limbs, a homologue of the R. 

 accessorius X is absent. 



