of the vagus. All these root bundles assemble into one trunk, whieh 
S6 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
By examination into the component character and central relations 
of this nerve, where it exists, it is found to be similar to those viscero- — 
motor components of X and IX which innervate striated muscles — 
(Johnston, :06, p. 203), such as the laryngeal muscles. These all — 
have their cells of origin (in the higher vertebrates at least) in a portion 
of the viscero-motor column ventrally separated from the rest and 
known as the nucleus ambiguus. While the motor nuclei of this 
region of the hind brain have been incompletely identified in Anolis, 
microscopic study has fully demonstrated that IX and X contain a 
very limited number of components such as innervate the laryngeal 
muscles and that these all pass ventrally with XII, which gives off 
no branches that cannot be directly traced to muscles of the ventral 
head region. 
It still remains to be demonstrated whether there is a . caudally 
extended motor nucleus ambiguus which contributes fibers to the spinal 
nerves innervating the muscles originally supplied by the accessorius. 
In the absence of such a relation, it would then be a question whether 
the trapezius muscle in Anolis is homologous to the one so named 
elsewhere. 
The apparent absence in Anolis of anything corresponding 4 the 
spinal accessory is an anomolous condition in reptiles, because, even 
making allowance for many misinterpretations depending on gross 
dissections, the universal mention of such a nerve in the literature - 
bearing on reptilian anatomy would indicate a greater development 
of the vago-accessorius group than is shown in Anolis. Fischer (752, 
p. 62) finds that the condition first described by Bischoff (732) is — 
realized in all the forms‘he studied, viz. that from 5 to 9 fine bundles, 
generally increasing in strength posteriorly, arise along an irregular 
line extending from the level of the second cervical nerve to the origin 
generally fuses with the vagus. In two species of the genus Salvator, 
however, this trunk remains separate, although it passes out through — 
the same foramen with the vagus. This independent course of the 
accessorius was also described by Bendz (?43) for Chelonia mydas. 
What Fischer calls thg accessorius includes, in addition to the ramus 
externus, fibers which have a distribution with the laryngeal branch of 
the vagus, or with the ramus recurrens vagi, or with both. The | 
ramus externus, which by gross methods is the only portion of the 
accessorius that can be followed to its distribution, was not ‘f 
by him in all forms. It was absent in Chamaeleo vulgaris and Agama 
spinosa. No mention was made as to whether there was a correlated 
