224 
IOWA ACADE^MY OF SCIENCE 
short distance in contact with each other, without any exchange of fibers. 
From the dorsal edge of the dorsal lateral line ganglion of the seventh 
nerve there passes posteriorly a branch that anastomoses with the rami 
supra-temporaJis and auricularis X. No such anastomosis has been 
reported in any other amphibian. It is very suggestive of the condition 
found in the Cyclostomata, where a branch of the lateral line component 
of the seventh nerve joins the ninth and tenth nerves. 
As has been noticed by previous writers the ramus palatinus and 
alveolaris VII of Siren arise from the ganglion by a common trunk, from 
w]iich there is given off posteriorly a nerve called by ’^vVilder the posterior 
palatine. This latter nerve passes in part to the pharyngeal region, Imt 
a part of it anastomoses with the ramus pretrematicus IX forming 
Jacobson ’s commissure. 
The lateral line constituents of the seventh nerve have in general the 
characteristic distribution. 
The discovery in Siren by Druener of a. levator arcuus hyoidei muscle, 
which he believes to he innervated by a branch of the ramus jugularis, 
is confirmed. 
The ninth and tenth nerve ganglia are nearly distinct from each other. 
The ramus communieans carries from the tenth to the seventh nerve gen- 
eral cutaneous fibers only. 
Pretrematic rami of five branchial nerves are found, but only three ' 
post-trematic rami. The various branches of the tenth nerve show a 
marked tendency toward an early departure from the main trunk; hence 
the diffuse character of a large part of the nerve as described and figured 
by Wilder and others. IMotor components of the posttrematic rami of 
the first and second liranchial nerves unite and innervate the ceratohyoi- 
deus internus muscle. The ramus intestinalis recurrens' is entirely 
motor. The sensory constituents usually found in this nerve in otlier 
Urodela leave the vagus ganglion as a distinct nerve united with other 
sensory fibers that form the fourth and fifth pretrematic nerves. The 
name, ramus sensorius recurrens X, is suggested for this nerve after the 
pretrematic and other pharyngeal branches are given off. 
The occurrence of persistent gills in Siren necessitates some special in- 
nervation of the branchial region. From the ninth or first branchial 
nerve a small general cutaneous component goes to the skin over the first 
branchial arch. From the second hrancrial nerve (vagus I) the levator 
branchiae 1 and depressor branchiae 1 and 2 muscles are innervated. 
It also sends general cutaneous branches to the first and second gills. 
From the third branchial nerve (vagus II) the levator branchiae 2 and 
3 and depressor branchiae 3 muscles are innervated. From the same 
nerve are given off general cutaneous branches to the third gill. 
