Herrick, WVerves of Silurotd Fishes. 197 
ductor of the maxillary barblet, and supplying this slip and the 
m. adductor mandibulae, 
The mandibular nerve as soon as formed turns laterally 
over the m. adductor tentaculi, just referred to, close under the 
eye then ventrally into the lower jaw, previously, however, 
sending a twig out laterally for the skin under the eye and an- 
other cephalad which follows the dorsal surface of the m. re- 
tractor tentaculi and its tendon and finally enters the maxillary 
barblet behind (caudad of) the nerves for this barblet which 
come from the r. maxillaris. This posterior nerve of the barb- 
let carries both general cutaneous and communis fibers. Before 
entering into the mandible the r. mandibularis divides into two 
branches, the smaller one running down external to the bones 
of the mandible, the larger one internal to them. | 
The external branch runs cephalad along the outer face of 
the mandible for its entire length, supplying the overlying skin 
and its terminal buds (the pit organs of this region it will be 
remembered are innervated by a similar twig, the cutaneous 
branch of the r. mandibularis externus VII) and the edge of 
the lower lip. It emits close to its origin a twig which pursues 
a rather peculiar course. It runs down external to the inser- 
tion into the mandible of the m. adductor mandibulae and then 
turns caudad along the dorsal surface of the mandible under 
the insertion of this muscle. Some of its fibers cross the cuta- 
neous branch of the r. mandibularis externus VII, passing in- 
ternally of it, for the skin over the dentary and angular bones. 
Others turn inward toward the buccal mucosa, which however 
they do not reach, but seem to break up over the articular and 
quadrate bones, probably for the overlying skin. 
The internal branch follows along the dorsal side of 
MECKEL’s cartilage (the r. mandibularis externus VII lying ven- 
trally of this cartilage) and farther forward enters the alveolar 
canal, giving off for its entire length filaments for the mucous 
lining of the mandible and for its teeth. Within the alveolar 
canal it descends between the dentary bone and MECKEL’s car- 
tilage and divides into several branchlets. One of these carries 
all of the remaining motor fibers and turns inward to supply 
