BRANCHES — BRANCHIAL NERVES OF FISHES 145 



The ramus hyomandibularis facialis issues from the cranial 

 cavity by a separate foramen and enters the facial canal of 

 Bridge's (79) descriptions, that canal being also traversed by 

 the vena jugularis, the arteria carotis externa, and a lymph 

 vessel. The nerve contains motor, lateralis, and communis 

 fibers, and also a bundle of the apparently general sensory 

 fibers above referred to, and as these several kinds of fibers 

 occupy definite regions of the nerve, the approximate composi- 

 tion of the larger branches of the nerve could be determined. 

 On issuing from the facial canal the nerve immediately receives, 

 or sends fibers into, the communicating branch, already de- 

 scribed, from the general sensory component of the vagus gan- 

 glion, this communicating branch apparently receiving all the 

 general sensory fibers of the hyomandibularis together with some 

 of its communis fibers. The nerve then runs posteriorly internal 

 to the hyomandibula and there gives off its ramus opercularis, 

 which contains both lateralis and motor fibers. This branch 

 runs posteriorly on the external surface of the musculus retractor 

 hyomandibularis of Danforth's ('13) descriptions, the motor 

 fibers going to that muscle and the lateralis ones to the little 

 organs called bj^ Collinge ('94) primitive pores, but which, for 

 reasons given below, I shall refer to as nerve pits. The ramus 

 hyomandibularis then passes across the dorsoposterior edge of 

 the hyomandibula and separates into its two branches, the 

 rami hyoideus and mandibularis. The ramus hyoideus contains 

 both lateralis and motor fibers and runs downward along the 

 posterior (morphologically external) edges of the cartilages of 

 the hyal arch, the lateralis fibers going to nerve pits on the gill 

 cover. The ramus mandibularis turns downward along the 

 lateral (morphologically anterior) surface of the hyomandibula, 

 and there separates into its internal and external branches. 

 The ramus externus contains all the remaining lateralis fibers of 

 the nerve, and runs downward along the lateral surfaces of the 

 symplectic and interhyal of Bridge's ('79) descriptions, and then 

 forward ventromesial to Meckel's cartilage, sending branches to 

 the organs of the hyomandibulo-mandibular laterosensory canal 

 and to certain of the nerve pits on the ventral surface of the 



