134 IOWA ACADEMY OF SCIENCE 



istence of a distinct Jacobson's commissure the evidence is not con- 

 vincing. It is certain that pharyngeal branches of the ninth nerve 

 come into close proximity with the posterior part of, or branches of, the 

 r. palatinus; apparently there is an anastomosing of branches. 



The glossopharyngeal — vagus complex in Necturus gives little evi- 

 dence of being in a primitive condition. The three branchial nerves in- 

 volved have been described by both Fischer (1. c.) and Druner (1. c.) 

 with an accuracy that needs little comment. The glossopharyngeal or 

 first branchial nerve shows characteristic pharyngeal, pretrematic and 

 posttrematic rami. It also sends a general cutaneous and motor branch 

 that anastomoses with the second branchial nerve. The second bran- 

 chial nerve (vagus 1) has well developed pharyngeal, pretrematic and 

 posttrematic rami. One motor and general cutaneous branch supply- 

 ing the levator and depressor muscles of the first gill and the overly- 

 ing skin receives the above-mentioned anastomosis from the ninth 

 nerve ; other branches supply the levator and depressor muscles of the 

 second gill; an anastomosis occurs with the third branchial nerve form- 

 ing the innervation of the levator and depressor muscles of the third 

 gill. The third branchial nerve (vagus 2) is very much reduced. In 

 it, however, may be recognized pretrematic and posttrematic rami of 

 communis fibers only, while the main part of the nerve forms an ana- 

 stomosis with a branch of the second branchial nerve as previously men- 

 tioned. These anastomoses between the branchial nerves in Necturus 

 are seen to be homologous to similar structures in Amblystoma. They 

 also occur in Spelerpes, but were overlooked by Miss Bowers. They 

 are not found in Siren. The ramus communicans from the IX-X to 

 the VII nerve contains in addition to the general cutaneous fibers a 

 small communis component, the distribution of which has been de- 

 scribed. The r. supra-temporalis arises from the ganglion along with 

 the motor nerve for the levator muscle of the first branchial arch, in 

 the manner described by Druner. The r. auricularis X has the usual 

 origin and distribution, being composed of general cutaneous and lat- 

 eral line fibers. The rami laterales dorsalis et medius are as in other 

 Urodela. The ramus intestino-accessorius X divides into three typical 

 branches: r. lateralis ventralis, r. intestinalis recurrens, and r. in- 

 testinalis. There seem to be unusual features in their distribution. 



Fischer states that the hypoglossal nerve in Necturus is formed from 

 branches of the second and third spinal nerves. Druner affirms that it 

 is the first and second spinal nerves that contribute to its formation. 

 The statement of Druner is confirmed, but the writers find that a small 

 branch of the third spinal nerA^es seems to unite with the trunk formed 



