464 HENRY C. TRACY 



THE CRANIAL NERVES 



The relations of the cranial nerves in clupeoids correspond in 

 general to those existing in other teleosts. The branches of the 

 nerves from the third to the tenth correspond closely to those 

 described by Herrick ('99) for Menidia. There are, however, 

 interesting special relations of certain branches of these nerves. 



The third nerve makes its exit from the cranium through the 

 foramen between the basisphenoid and prootic bones; the fourth 

 nerve penetrates the center of the alisphenoid bone (fig. 8); the 

 sixth nerve gains access to the eye-muscle canal by penetrating 

 the medial plate of the prootic bone. 



The ganglia of the trigeminofacial complex lie in the ganglionic 

 fossa and give off branches which pass through the prootic bone 

 across the surface of the bulla (fig. 3) . In addition to the branches 

 mentioned above (p. 457), a recurrent branch is given off from 

 the lateral part of the ganglion. It immediately divides into 

 two rami which pass laterally to the back of the ganglionic fossa 

 and through the articulation between the prootic and sphenotic 

 bones, and enter the lateral recess of the skull. The more lateral 

 of these rami courses obliquely across the floor of the recess to 

 its posterior lateral corner where it supplies the hyomandibular 

 lateral-line canal (fig. 3, RVII). The medial ramus curves 

 gradually upward through the recess and penetrates the lateral 

 plate of cartilage, thus entering the perimeningeal tissue (fig. 9) 

 of the cranial cavity; it continues upward through this tissue, 

 slanting slightly backward, and appears to form a plexus with 

 the recurrent branch of the vagus. It also contributes to the 

 supply of the sac-like expansion of the lateral line canal which 

 occupies the temporal foramen. The medial branch has a course 

 similar to that of the ramus recurrens facialis which Herrick 

 describes in Menidia as made up of communis fibers. 



In sections of the head of adult Pomolobus, I was able to trace 

 branches to the bay-like expansions of the lateral-line canal as 

 described above. These bays are so large that they may not 

 function exclusively as lateral-line structures. The termination 

 in them of the recurrent facial branches is therefore not neces- 



