willard: cranial nerves of anolis carolinensis. 69 



demonstrable in VII and are not generally considered pi-esent in rep- 

 tiles. They are, however, found in the Amphibia (Norris and others), 

 and their distribution there would agree quite closely with the reptiles 

 if it were discovered that a trace of the cutaneous component were 

 carried to the skin in this sympathetic ramus, for the course of this 

 ramus is superficial, and anteriorly it anastomoses freely with the 

 cutaneous fibers of V. The conditions for study here were not such that 

 a failure to observe this would preclude the possibility of a very few 

 cutaneous fibers taking this course, should the central relations indi- 

 cate a connection with the somatic sensory tract. The hyomandibu- 

 lar just distal to the crossing of the sympathetic divides into the motor 

 ramus hyoideus and the sensory chorda tympani (Plate 7, figs. 20, 

 21, hy. and cd. tym.). 



(a) Ramus hyoideus \hy.). After parting with its sensory compo- 

 nents, the motor part of the hyomandibularis continues its course 

 to the muscles supplied by it. As this nerve reaches the depressor 

 mandibular (digastric) muscle it divides into two branches for dorsal 

 and ventral distribution (Plate 3, figs. 6, 7, hy., and Plate 7, fig. 

 23). The final distribution of this nerve is well showni in figure J, 

 which is a drawing from a mounted dissection that had previously 

 been treated with vom Rath's mixtures. This shows that the digas- 

 tric, sphincter colli, and the most posterior part of the mylo-hyoideus 

 are innervated by ramus hyodeus (motor VII). This agrees with 

 what Ruge ('97, p. 331) found in Varanus, although Watkinson (:06) 

 was not able to discover it in her dissection. 



Ruge ('97), in his extensive monograph on the facial nerve in the 

 vertebrates, considers the mylo-hyoideus muscle in reptiles as belong- 

 ing to the inner\ation field of motor VII, and he finds this demonstra- 

 ble in Hatteria (p. 325), where the ventral ramus of VII is figured as 

 extending almost to the end of the jaws. In the same form the ramus 

 mylo-hyoideus of V lea^•es the jaw in the manner typical of that nerve, 

 but Ruge considers it wholly cutaneous sensory. In the alligator 

 the same muscle is innervated by the motor fibers carried in the ramus 

 mylo-hyoideus of V, and Ruge (p. 381) concludes that V has recei^^ed 

 these " intracranially " from VII. Comparing with the amphibian 

 Amphiuma, as described by Norris (:08), the motor components in 

 ramus hyoideus VII of Anolis are directly homologous with the ramus 

 jugularis of Amphiuma, which innervates the digastric, sphincter colli 

 and posterior part of the mylo-hyoideus muscles, leaving the anterior 

 part of the mylo-hyoideus to be inner\'ated by the ventral division of 

 the main mandibular, which is evidently the ramus mylo-hyoideus of 

 V as described in Anolis (p. 61). 



