Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 279 



obliquus ventralis. None of them, so far as could be determined, 

 anastomosed with the branches of the ramus posterior of the arch. 

 The one large branch was given off shortly before the nerve 

 reaches the distal end of the epibranchial. It turned downward, 

 internal to the bases of the rays of the anterior row of gill fila- 

 ments, and then across the antero-lateral face of the ceratobranchial 

 of the arch. There it continued distally to the distal end of the 

 arch, giving off numerous small branches, apparently destined to 

 supply the dermal processes or spines of the arch. None of the 

 branches were traced definitely into those processes, and the 

 branches of the nerve were much less numerous than the processes. 

 From the base of the ramus posttrematicus two motor branches 

 were given off, one to the anterior division of the internal levator 

 of the arches, and one to the external levator of the first arch. 



10. Nervns Vagus. 



The root of the nervus vagus (v) and that of the nervus lineae 

 lateralis vagi (nil) issue together from the vagus foramen, the 

 nervus vagus lying ventro-posterior to the nervus linege lateralis. 

 Both roots arise from the lateral surface of the medulla, the root of 

 the lineae lateralis arising antero-dorsal to the root of the vagus, 

 and slightly dorso-posterior to the root of the acusticus. The 

 vagus arises by several separate rootlets. Both roots run at first 

 backward and downward, and then turn laterally, backward, and 

 downward as they pass through their foramen. 



No intracranial branches were found arising from either the 

 vagus or the lateralis roots, my work agreeing in this with 

 Stannius' (No. 70, p. 85). From each of the two roots, however, 

 as they pass through their foramen, a nerve arises, which Stan- 

 nius seems to have overlooked. The two nerves lie close together 

 and both turn laterally and dorsally as they issue from the skull. 

 The branch of the vagus, which, according to Herrick (No. 38, 

 p. 165), is, in Menidia, partly or wholly formed by communis 

 fibers from the root of the glossopharyngeus, runs upward along 

 the outer surface of the anterior edge of the trunk muscles, lying 

 slightly anterior to the branch of the nervus lineae lateralis. It 

 passes lateral to the posterior process of the intercalar, and there 

 sends a branch forward toward the origin of the levator operculi 



