Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 215 



the ramus posterior also penetrated the muscles ; this being more 

 particularly the case on the second arch. The obliquus of the 

 fourth arch seemed to be innervated by the ramus anterior of the 

 third arch instead of by that of the fourth arch. 



The TransversusVentralis Anterior arises from the concave, 

 mesial surface of the spoon-shaped anterior end of the fourth cerato- 

 branchial of one side of the head, and extends across the middle 

 line of the head to the corresponding surface of the ceratobranchial 

 of the opposite side. The line of origin lies dorsal to the line of 

 insertion of the fourth obliquus, and the muscle lies ventral to the 

 anterior ends of the ceratobranchials of the fifth arch, curving 

 downward to pass below them. Its innervation, like that of the 

 obliquus of the fourth arch, could not be satisfactorily determined. 

 It seemed to be innervated by the ramus anterior of the third arch 

 rather than by that of the fourth arch, but the latter nerve ran 

 forward close to it, along its dorsal surface, and delicate branches, 

 that perhaps innervated it, may have been missed in the dissection. 



The Transversus Ventralis Posterior, called by Vetter the 

 pharyngeus transversus in the teleosts described by him, is a flat, 

 thin muscle, which arises from the mesial surface of the ventral 

 process or wing of the fifth ceratobranchial, and is inserted, with its 

 fellow of the opposite side of the head, on a median, longitudinal 

 tendon. The dorsal edge of this median tendon projects upward, 

 as a ridge, between the mesial edges of the two pharyngeal bones, 

 and between two small, anterior, longitudinal prolongations of the 

 muscles of the oesophagus, to which it gives insertion. Anteriorly 

 the median tendon separates into two parts, each of which is 

 inserted on the fifth ceratobranchial of its own side of the head, 

 at the anterior end of the mesial surface of the ventral process or 

 wing of the bone. The point of insertion of the tendon lies ante- 

 rior to the surface of origin of the transversus, and antero-mesial 

 to the surface of insertion of the pharyngo-clavicularis externus. 



The muscle is innervated by a branch of the nerve of the fifth 

 arch, that is, by a branch of the ramus posttrematicus of the fourth 

 vagus nerve. 



The anterior end of the Constrictor CEsophagei shows several 

 muscles either in process of absorption or in process of differentia- 

 tion, whichever it may be. The muscle already described as the 



