BRAIN AND CRANIAL NERVES OF BDELLOSTOMA DOMBEYI, 167 
broad base, and is short, blunt, and flabby. It has, in conse- 
quence, much more space inside of it than the other three, 
the nerve does not pack it closely as it does them, and its fine 
fibres are lost in the connective tissue. In addition to sup- 
plying the tentacle and the skin immediately around it, the 
nerve to the fourth tentacle has a large cutaneous branch 
that curves caudad, and supplies the lip at the lower angle of 
the mouth. 
The deep branch is purely motor. It runs cephalad 
beneath m. palato-ethmoideo-profundus, into which it 
sendsa large branch. This branch, after supplying the muscle, 
forks, sending a dorsal branch to supply m. nasalis and m. 
palato-ethmoideo-superficialis, and a ventral branch 
to m. tentacularis posterior. The main branch turns 
ventrad and forks, sending one branch running along the 
lateral face of m. copulo-ethmoidalis, into which it sends 
twigs, and then into m. copulo-tentaculo-coronaris; 
the other branch runs straight forward to end in 
m. ethmoideo-nasalis. 
R. maxillaris posterior is sensory, and helps to supply 
the mucous membranes of nose and mouth. It has a very 
short trunk, dividing, before it reaches the sub-ocular arch, 
into r. nasalis and r. palatinus. R.nasalis passes over 
the sub-ocular arch and under r. ophthalmicus, lying so 
close to this nerve that Firbringer thought it arose from it. 
It moves toward the nasal tube just in front of the olfactory 
capsule, and runs cephalad along its side, giving off several 
branches, thus supplying the posterior two-thirds of the tube. 
R. palatinus passes under the sub-ocular arch, and runs 
cephalo-ventrad inside the palatine bar, giving off several 
twigs to the pharynx by the way. At the anterior end of 
m. velo-quadratus it divides into four small branches and 
innervates the roof of the mouth. This nerveis Firbringer’s 
palatine branch of r.medius maxillaris externus. 
R. Mandibularis (Fiirbringer’s r. posterior maxillaris 
externus V + r. maxillaris internus V).—This nerve is 
mainly concerned with the innervation of the dental plate 
vo. 49, part 1.—NNW SERIES. 13 
