willard: cranial nerves of anolis carolinensis. 87 



reduction of the posterior roots; if such a reduction occurred in these 

 two species, they would be in correspondence with Anolis. Fischer 

 demonstrated the ramus externus definitely in nine other species of liz- 

 ards and in the crocodile. Bischoff ('32) and Vogt ('39) had described 

 this ramus externus as supplying a small twig to the cervical muscle, 

 but this could not be expected, and was not verified by Fischer. 



Fiirbringer ('76, p. 649) in his account of the innervation of the 

 shoulder muscles of saurians refers to the part taken in their innerva- 

 tion by the vago-accessorius as though it w^ere a regular feature to be 

 met with in all forms. The ramus externus is distributed, he says, 

 to the ventral half of the capiti-cleido-episternalis (capiti-dorso- 

 clavicularis), where it as a rule anastomoses with the cervical plexus 

 of the anterior spinal nerves. 



INIore recently Osawa ('98, p. 616) has described in Hatteria a 

 spinal accessory having the typical superficial origin, which extends 

 caudally as far, as the third spinal nerve. This accessory joins X, 

 and distal to the ganglion there is given off a weak ramus internus 

 and a strong ramus externus, the latter going to innervate the muscle 

 capiti-dorso-clavicularis. Schauinsland's (:03, Taf. VIII, fig. 70) 

 observation on the embryo of the same form practically coincides with 

 Osawa's description. 



There appears to be some confusion in Watkinson's (:06) account 

 of this nerve in Varanus. She says (p. 467) " the ramus externus vagi 

 innervates the muscle sterno-cleido-hyoideus near its origin from the 

 skull. This muscle also receiving innervation from the third cervical 

 nerve, the end fibers forming an intricate sling with those of the ramus 

 externus." Reference to her Plate XII, figs. 10 and 11, shows that 

 the author means " m. capiti-cleido-episternalis." Another ambiguity 

 rests in the use of the term "m. cucullaris" (Plate XII, fig. VIII) for 

 the most superficial neck muscle. This evidently corresponds to the 

 sphincter colli of x\nolis and, like the latter, is innervated by VII. 



Notwithstanding the great number of papers that have appeared 

 on the morphology of the nervus accessorius, the subject is far from 

 settled, and, in view of the great range of variation in the anatomical 

 relations of roots and peripheral nerves, the necessity of microscopical 

 analysis is obvious. Lubosch's ('98 and '99) extensive review of the 

 subject in vertebrates from the standpoint of comparative anatomy 

 only tends to emphasize the fragmentary nature of our knowledge 

 regarding this region in amniotes. 



