CRANIAL NERVES OF SIREN LACERTINA 297 
and may emerge from the skull by- a special foramen in the petro- 
sal, or, running more anteriorly, they may pass out with the 
trunecus supraorbitalis (fig. 11). This small group of lateral 
line fibers may or may not be accompanied by general cutaneous 
fibers. On emerging from the skull the nerve turns sharply pos- 
teriorly and runs a short distance along the dorsal border of the 
lateral wing of the parietal bone (figs. 12, 13), then passes 
dorsally through the masseter muscle to take a position just be- 
neath the skin on the side of the head at about the level of the 
dorsal border of the skull (fig. 14). Its course is thence posteri- 
orly to an anastomosis with the rami supratemporalis et auricularis 
X. Just what neuromasts of the occipital series are supplied by 
this branch it does not seem possible to determine. In some in- 
stances a branch of the nerve leaves the main portion at the emer- 
gence from the skull and supplies some neuromasts of the supra- 
orbital series. Between the supraorbital series of neuromasts 
and the occipital series there seems to be no dividing line exter- 
nally, a condition fully borne out in the innervation. It seems 
however, that most of the neuromasts supplied by this union of the 
seventh nerve constituent with the rami supratemporalis et auric- 
ularis X belong to the occipital series, although it is reasonable 
to suppose that a few of the more anterior ones are supraorbital. 
This anastomosis seems to be peculiar to Siren among the amphib- 
ians. Johnston (’05 b) shows in Petromyzon a lateral line anas- 
tomosis between the seventh and the ninth-tenth nerves, and 
in Lampetra between the seventh and tenth nerves. He suggests 
that this anastomosing branch of the seventh nerve with its neuro- 
masts may represent the ramus oticus of fishes and the organs 
supplied by it. Such an explanation for the condition in Siren 
seems plausible. 
10. The ramus alveolaris VIT 
From the extreme anterior end of the geniculate ganglion the 
communis fibers of the facialis emerge and pass ventrally through 
the posterior portion of an elongate slit-like opening between the 
orbitosphenoid (petrosal) cartilage medially and the quadrate 
cartilage laterally (fig. 12, alv.-pal.). Immediately after passing 
