Herrick, Cranial Nenrs of the Cod Fish. 285 



and dorsally of the first mentioned nerve, and finally the 

 dorsal branch of the r. mandibularis V, dorsally and later- 

 ally of the r. mandibularis externus VII. The nerves do not 

 mingle, though they lie adjacent. 



The dorsal branch at the tip of the mandible distributes 

 one twig in the alveolar canal of the dentary bone ; the re- 

 mainder spreads out under the skin of the lower lip. These 

 fibers unquestionably distribute mainly to the terminal buds with 

 which the lower lip, like the upper, is abundantly supplied. 



The ventral branch sends twigs down to the skin of the 

 tip of the mandible, these accompanying the branches from the 

 r. mandibularis externus VII through the dentary bone into 

 the canal and thence ventrad to the skin. At the level of the 

 first mandibular canal organ all of the remainder of this ventral 

 branch turns inward and slightly backward to enter the mental 

 barblet. 



The structure of this barblet, though but imperfectly 

 shown in my preparations, is very interesting. The epidermal 

 covering is a very thick epithelium, consisting in places almost 

 wholly of large terminal buds crowded close together. Beneath 

 this is a thin, but dense, chorium, then a wide space between 

 this and the thin supporting rod filled completely with nerve 

 fibers from the mandibularis V nerves of the two sides of the 

 head. 



A large proportion of these fibers are unquestionably com- 

 munis nerves. It is probable that not all are such and that the 

 barblet has an extensive general cutaneous innervation as well, 

 since among the very fine nerve fibers are a few scattered ones 

 of large size — a condition characteristic of general cutaneous 

 nerves and one to have been expected on a pnori grounds. 



We have, then, traced communis nerves into the r. man- 

 dibularis V at its proximal end and traced this nerve distally 

 into structures known to be typically innervated by the com- 

 munis system. The course of these communis fibers can there- 

 fore be safely inferred, even though we have not been able to 

 distinguish them from the accompanying general cutaneous 

 nerves for their entire course. 



