THE DOGFISH 



369 



an external mandibular, and a hyoidean. Of these, it is the 

 internal mandibular which corresponds to the mandibular 

 of the frog. The palatine and hyomandibular branches 

 pass together through the same foramen with the main 

 part of the fifth. The eighth or auditory nerve passes 

 into the auditory capsule to supply the inner ear. The 

 ninth or glossopharyngeal nerve arises from the side of 

 the medulla behind and rather below the eighth, passes 



vm. \s v w& yiop. fop- 



Js Whm. sp\ VHpsp.', Wei"-\ Vmd.. 



Vfrhi. VMi-m, 



Fig. 264. — A diagram of the distribution of certain cranial nerves in 

 the dogfish. The nerves shown in black are distributed to the 

 system of sense-tubes which includes the neuromast ampullae 

 (P- 373)> lateral line, and labyrinth of the ear. The shaded 

 nerves are distributed to visceral arches. 



V.-X., Roots of the nerves; V.md., V.mx., V.op,, mandibular, maxillary, and 

 (superficial) ophthalmic branches of the fifth nerve; Vop'., deep ophthalmic 

 nerve, not mentioned in the text, inconspicuous in the rough hound, but large 

 in many other fishes (p. 378) ; Vll.b., VII. e.m., buccal and external mandibular 

 branches of the seventh nerve, distributed to some of the neuromast ampullae ; 

 VII. hd., Vll.i.m., VII. op., Vll.pal., VII.psp., hyoidean, internal mandibular, 

 ophthalmic, palatine, and prespiracular branches of the seventh nerve ; Vll.hm., 

 postspiracular division of hyomandibular branch of seventh nerve; X.I., 

 X.v., lateral line and visceral branches of the tenth nerve ; g.s., gill slits ; 

 m. t mouth ; sp., spiracle. 



through a passage in the cartilage of the auditory capsule, 

 emerges by its foramen behind the capsule, and turns 

 down the first branchial arch, after giving off a small 

 prebranchial branch to the hyoid arch. The tenth or 

 vagus nerve arises by a number of roots immediately 

 behind the ninth. It leaves the skull by a foramen beside 

 the occipital condyle, and runs backwards along the anterior 

 cardinal sinus, lying just median to that vessel, immediately 



