DISSECTION OF THE SHARK 33 



(4) For the internal ear from the nervus acusticus. 



(5) For the lateral line organs of the temporal canal from 

 the ramus supratemporalis IX. 



(6) For the lateral line canal of the body from the ramus 

 supratemporalis, ramus dorsalis, and ramus lateralis X. 



The nerve-fibers of this system which supply the irregularly 

 arranged ampullae of the head distribute in company with those 

 for the lateral line canals of the head. 



19. Many of the peripheral nerve-trunks are mixed in the sense 

 that they contain functionally different components. These 

 components may come from roots of several different nerves by 

 anastomoses peripherally of the ganglia. Some of the more 

 important peripheral nerves of the dogfish are as follows: 



(1) The supra-orbital trunk, containing the r. ophthalmicus 

 superficialis V (general cutaneous) for the skin of the top of the 

 head, and lateral line fibers for supra-orbital lateral line organs 

 (the r. ophthalmicus superficialis VII); (2) r. ophthalmicus 

 profundus V (general cutaneous), passing through the middle 

 of the orbit, beyond which it anastomoses with the r. ophthal- 

 micus superficialis V to supply the skin of the snout (the 

 superficial and deep ophthalmic branches of the V nerve to- 

 gether correspond approximately with the ophthalmic branch 

 of the human trigeminus) ; (3) the infra-orbital trunk, passing 

 across the floor of the orbit, below which it divides into the r. 

 buccalis VII (lateralis) for infra-orbital lateral line organs, r. 

 maxillaris V (general cutaneous) for the skin of the upper jaw, 

 and r. mandibularis V (general cutaneous and motor) for the 

 skin and muscles of the lower jaw; (4) r. palatinus VII (visceral 

 sensory) for the mucous membrane and taste-buds of the roof 

 of the mouth (represented by the great superficial petrosal 

 nerve of the human body) ; (5) the hyomandibular trunk, pass- 

 ing behind the spiracular cleft to the region of the hyoid arch 

 and lower jaw, containing the r. mandibularis internus VII 

 (visceral sensory) for taste-buds and mucous membrane lining 

 the lower jaw, motor VII fibers for muscles of the hyoid arch 

 (r. hyoideus), and lateral line fibers for hyomandibular lateral 

 line organs (r. mandibularis externus VII). The visceral 

 sensory and motor fibers correspond with the facial trunk of 

 the human body. 



