308 H. W. NORRIS 
exclusively, but the writer has shown (11) that there is a com- 
munis constituent also in Spelerpes. In Amphiuma he has found 
the ramus communicans to be mostly if not wholly general cuta- 
neous. In Necturus Norris and Buckley find the conditions 
similar to those in Amblystoma and Spelerpes. In Triton Coghill 
finds no motor fibers in the ramus communicans. 
The ramus communicans of Siren arises in different ways. It 
may be found entering the ganglion along the dorsal border of 
the ramus posttrematicus IX, becoming ganglionated at a point 
where the anterior border of the third (Xr.2) IX—Xth group of 
rootlets enters the ganglion. It is clear that no motor fibers enter 
the nerve, as all its fibers become interrupted, that is, become 
ganglionated, in their course through the ganglion, in marked 
contrast to the neighboring motor tract of the glossopharyngeal 
root. Their continuation into the root of the vagus is in that 
portion where most if not all of the general cutaneous fibers are 
situated. ‘The communicans may enter the ramus posttrematicus 
IX near the exit of the latter from the ganglion. In that case, 
incorporated in the nerve, its course through the ganglion is not 
so easily followed. In one specimen the nerve enters the gan- 
glion on one side as a single nerve; on the other side it divides into 
three parts, one portion entering the ganglion in the typical way, 
a second joining the posttrematicus [X, and the third passing 
posteriorly into the ramus auricularis X. In specimens, where 
the fiber differentiation is such that communis and general cuta- 
neous components can be differentiated from each other, the 
communicans can be traced beyond question into the general 
cutaneous constituent of the vagus roots. In one specimen the 
communicans of the left side is large and general cutaneous fibers 
can be traced from the vagal root through the ganglion and base 
of the ramus pretrematicus IX into the ramus communicans; on 
the right side the communicans is totally lacking and no general 
cutaneous constituent enters the glossopharyngeal region of the 
ganglionic mass. 
Driiner and Fischer have called attention to the small size of 
the communicans in Siren. The writer finds that the number 
of fibers in the ramus is wholly inadequate to furnish all the gen- 
