The Cranial Nerve Components of Petromyzon. 155 
The mixed ramus arising lateral to this runs ventro-laterally 
between the eircular pharyngeal muscles and the lateral body musc- 
les (Fig. 2). Turning, it runs backward and slowly downward and 
grows rapidly smaller, probably from giving twigs to the pharyngeal 
muscles. The smaller part finally reaches the dermis in 385, just 
in front of the longitudinal groove which connects the gill slits; i. e. 
in the region of the spiracular cleft. I do not find this nerve con- 
nected with the facialis at this point as HATSCHER states, but other- 
wise my description agrees with his figure. 
Returning now to the trigeminus ganglion a little in front of 
the mandibular rami (299), the portion of the ganglion belonging to 
the ramus maxillaris is quite separate from that of the profundus 
(see below). The greater part of the motor root ceontinues forward 
in this ganglion. The ramus maxillaris goes forward between the 
pharyngeal and body muscles (Fig. 1) and in 252 begins to divide. 
Two small branches not shown in the plate are given off here. One 
reaches the skin and is traced forward to 227; the other is lost in 
the oblique museles.. The fibers of the maxillaris now come to be 
arranged in two bundles, an outer which is direeted more down- 
ward, and an inner more forward. The two bundles gradually sepa- 
rate (240) but continue nearly parallel. The outer ramus sends two 
small rami ventrally which reach the skin; the inner sends two or 
three twigs into the oblique muscles. At 220 a large branch is 
given of from the main inner ramus ventro-mesially. It runs through 
the pharyngeal muscle, cerosses a large blood sinus and reaches the 
dorsal end of the V-shaped cartilage mentioned above. Situated in 
the dermis overlying this cartilage it runs backward. At about 240 
it divides into a mesial branch which bends into the tongue and is 
soon lost, and a lateral branch which continues backward and in- 
clines downward. It runs some distance above the m. copulo-glossus 
obl., rises higher in the wall of the septum and farther from the 
muscle, grows gradually smaller and smaller, and as the septum 
srows higher and thinner the nerves of the two sides run as fine 
strands close together near its apex and are finally lost about 350. 
From 220 the mesial ramus of the maxillaris continues forward to 
188 where it turns mesially and divides into several branches which 
are distributed to the muscles and roof of the buccal funnel. 
The lateral branch of the maxillaris continues forward and 
downward and gives off branches ventrally at 211, 200, 194 and 164 
and divides into several branches which eontinue forward. All the 
