292 H. W. NORRIS 
4. The truncus supraorbitalis 
Passing anteriorly from the dorsal lateral line ganglion the 
lateral line fibers, already separated into a dorsal and a ventral 
group (fig. 11), are joined by general cutaneous fibers from the 
Gasserian ganglion (the third group of fibers mentioned under the 
head of the trigeminal nerve). It is questionable whether any 
general cutaneous fibers should be considered as a constituent 
part of the dorsal or supraorbital division in Siren. The general 
cutaneous branches which appear to spring from this nerve, in 
reality come from the fibers associated with the ventral or infra- 
orbital trunk, or perhaps it were better stated that they pass 
directly from the Gasserian ganglion dorsally, right and left, 
around the lateral line trunks, some of them associating with 
lateral line branches of the latter nerves. Close to the ganglion 
all the tracts of fibers and nerves are so closely associated that 
only by most careful examination and comparison of the condition 
in different individuals can the true relations be determined. 
Three or four branches containing general cutaneous fibers arise 
seemingly from the supraorbital trunk in the vicinity of the gan- 
glion. In Amphiuma similar branches of general cutaneous and 
lateral line composition, arising from the base of the supraorbital 
trunk, were considered by the writer as equivalent to the ramus 
oticus of fishes. In both species the lateral line constituent of 
these branches supplies the posterior part of the supraorbital 
series of neuromasts, and in Amphiuma the extreme dorsal end 
of the infraorbital series. In Siren few if any of the infraorbital 
‘series of neuromasts are innervated from this group of nerves. 
The general cutaneous portions of these nerves supply the skin in 
the regions of the neuromasts innervated by their lateral line com- 
ponents. The exact origin of the small nerves from the base of 
the supraorbital trunk, and from the infraorbital as well, is ex- 
tremely variable. Anteriorly from this region of the supraorbital 
near the ganglion, where these small nerves already mentioned are 
given off, the nerve is exclusively lateral line in composition, and 
therefore represents the ramus ophthalmicus superficialis VII (os.). 
It continues anteriorly between the pterygoid and masseter muscles 
