NoRRls, Nerves of Amphiuma. 545 



enters the brain by two rootlets which seem to correspond in 

 origin to the median and ventral rootlets of the lateral line com- 

 ponent of the facial nerve. The second group of rootlets consists 

 of general cutaneous (X {20))^ communis {X (2b)) and motor 

 (X{2c)) rootlets. The communis rootlet carries all the communis 

 fibers of the second (X.i.) and third (X.2.) branchial nerves and 

 of the r. intestino-accessorius. The general cutaneous compo- 

 nent supplies fibers to the glossopharyngeus nerve, to the ramus 

 communicans cum faciali, to the r. auricularis X, and to the 

 second and third branchial nerves. The motor rootlets supply 

 the secondhand third branchial nerves and contribute fibers 

 to the r. intestino-accessorius. The third (X (5)), fourth {X (4)), 

 and fifth (X(5)), groups of rootlets are exclusively motor. They 

 may be considered as constituting one root. With some fibers 

 from the second group of rootlets they form the motor component 

 of the r. intestino-accessorius. In some individuals the fifth root 

 is lacking or extremely attenuated on one side (fig. 23). In one 

 specimen there was found a posterior vagal rootlet emerging with 

 the first spinal nerve. A comparison of the IX-X roots in 

 Amphiuma with those in Necturus and Amblystoma is shown 

 in the following table : 



The IX-X ganglion is elongate in shape, somewhat oval pos- 

 teriorly, and anteriorly flattened wedge-shaped where it passes 

 under the ear capsule. The nerves leaving the ganglion are 

 eight in number. 



b. The ramus communicans rum faciali. — Of these the ramus 

 communicans cum faciali, or anastomosis X ad VII, will be con- 

 sidered first. It would appear from the diff^erent accounts given 

 that this trunk in origin and composition is subject to considerable 

 variation in the amphibians. It is usually described as leaving 

 the ganglion in a common trunk with the glossopharyngeus proper. 

 KiNGSLEY and Druner both so describe it in Amphiuma, but I 



