CRANIAL NERVES OF SIREN LACERTINA 311 
Amphiuma the writer finds that the ramus pretrematicus IX 
anastomoses with the ramus palatinus VII and the ramus alveo- 
laris VII; two anastomoses with the latter. Sometimes Jacob- 
son’s anastomosis is double. In one instance there was an anas- 
tomosis of the ramus pretrematicus IX with the hyomandibular 
trunk of the facialis. In some cases there developed out of the 
anastomoses a definite plexus between the IXth and VIIth nerves. 
In Amphiuma the ramus communicans appears to have no com- 
munis fibers. In Siren the interchange of fibers has become re- 
duced, and, since the palatine and alveolar nerves issue from the 
skull in a common trunk, Jacobson’s anastomosis connects with 
this trunk, thus combining in one anastomosis all the different 
connecting communis branches in Amphiuma. In Amblystoma 
Coghill finds the ninth nerve anastomosing with the ramus pala- 
tinus VII (palatinus caudalis), forming Jacobson’s anastomosis, 
and sometimes also the ramus pretrematicus IX with the ramus 
alveolaris VII. In the ramus communicans he finds a communis 
constituent that joins the ramus alveolaris VII. In Triton he 
finds a Jacobson’s anastomosis, but no glossopharyngeal anas— 
tomosis with the ramus alveolaris VII, and apparently the ramus 
communicans consists of general cutaneous fibers only. In Spe- 
lerpes Miss Bowers does not find a Jacobson’s anastomosis. The 
writer confirms this to the extent that there occur anastomoses 
between the smaller branches only of ramus pharyngeus [X and 
ramus. palatinus VII. Miss Bowers recognizes only general 
cutaneous fibers in the ramus communicans of Spelerpes, but the 
writer finds a large communis constituent that joins the alveolaris 
as in Amblystoma. The anastomoses in Necturus seem to be 
about identical with those in Spelerpes. In Plethodon ‘there is 
evidently a definite Jacobson’s anastomosis, and the ramus com- 
municans has a communis element that joins the ramus alveolaris. 
Thus it is seen that there are three possible communis anas- 
tomoses between the glossopharyngeal and the facial nerves: 
(1) a communis component may occur in the ramus communicans, 
connecting the glossopharyngeal ganglion and the ramus alveo- 
laris VII (Amblystoma, Spelerpes, Plethodon, Necturus); (2) 
Jacobson’s anastomosis between the ramus pharyngeus IX and 
