Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 281 



separated from the main root of the nervus, and running distally 

 along the nerve, and then along the inner surface of its ganglion, 

 joined the nerve again toward the distal end of the ganglion. 

 The other bundle arose from the ventro-mesial surface of the 

 main root of the entire nervus, before the first vagus nerve had 

 separated from it, and running ventro-posteriorly, along the in- 

 ternal surface of the second, third and fourth ganglia, broke up 

 into several branches, all of which joined the three posterior 

 vagus nerves beyond their ganglia. In the final and most perfect 

 dissection made this bundle separated into four branches, one of 

 which went to the second vagus nerve some distance beyond its 

 ganglion, a second to the third vagus close to its origin from its 

 ganglion, and the third and fourth to the fourth vagus. The 

 fibers of these two bundles thus did not pass through any of the 

 ganglia of the nerves to which they were related, resembling in 

 this the bundle of fibers found by Dr. Dewitz on the nervus 

 glossopharyngeus, and already described. 



The First Vagus Nerve usually separates, immediately beyond 

 its ganglion, into anterior and posterior parts, the latter being the 

 posttrematic branch of the nerve, and the former the united 

 pharyngeal and pretrematic branches. Lying close together the 

 two parts run downward, backward and laterally between the 

 anterior and posterior divisions of the internal levator of the 

 branchial arches, and there separate from each other, the anterior 

 division also separating into its pharyngeal and pretrematic parts. 



The pharyngeal branch of the nervus runs downward and for- 

 ward, mesial to the interarcualis dorsalis that connected the first 

 and second arches, between that muscle and the antero-lateral 

 edge of the obliquus dorsalis of the second arch, and separates 

 into two branches. One of these two branches, in the specimen 

 examined, was distributed entirely to the tissues along the an- 

 tero-ventral face of the second infrapharyngobranchial, and the 

 other partly to those same tissues and partly to tissues along the 

 oral edge of the postero-mesial face of the first epibranchial. 

 Both branches lie postero-mesial to the suprapharyngeal process 

 of the first epibranchial and hence also to the suprapharyngeal 

 element of the same arch. 



The pretrematic branch of the nervus runs forward, laterally 



