CoGHiLL, Cranial Nemes of Amblystoma. 285 



3. The difference in the origin of the communis VII root 

 in Urodela and Anura cannot be explained on the basis of 

 correlated changes in the lateralis VII and auditory nerves. 

 The relations of the geniculate ganglion in Siren is of obscure 

 significance, but it may have important bearing on the mor- 

 phology of the r. alveolaris and r. mandibularis internus. 



4. The r. palatinus of Amblystoma, and probably of 

 other Urodela, corresponds with the r. palatinus of the tadpole 

 in the division posteriorly of the internal nares into two divi- 

 sions each ot which anastomoses with a general cutaneous 

 branch of the trigeminus. 



5. The r. ophthalmicus profundus of Amblystoma per- 

 forms the function of the r. maxillaris and r. ophthalmicus 

 profundus in the tadpole of the frog. The terminal rami of 

 the r. ophthalmicus profundus in Amblystoma are not exact 

 equivalents to those of the tadpole and should not have the 

 same nomenclature as the latter. 



6. The r. maxillaris of Urodela is homologous with the 

 "accessory" branch of the trigeminus in the tadpole, and both 

 these nerves probably represent the r. maxillaris of fishes much 

 diminished in function. 



7. The lateral line nerves, r. ophthalmicus superficialis, 

 r. buccalis and r. mentalis, appear to be remarkably constant in 

 Urodela. They are derived from the lateralis VII root. 



8. The r. alveolaris is a pre-spiracular nerve and is not 

 the homologue of the r. mandibularis internus of Anura and 

 fishes. The latter nerve is post-spiracular. 



9. The sensory part of the r. post-trematicus VII may be 

 represented occasionally in some Urodela by a small nerve 

 which anastomoses with the r. pre-trematicus IX. 



10. V\[il'DKk's posterior palatine of Siren is of doubtful 

 significance. It may not represent the r. palatinus caudalis of 

 Amblystoma. 



11. The most cephalic root of the IX+X complex in 

 Urodela is the lateralis X root. It fuses quickly with the root 

 of the glossopharyngeus. The posterior root of the complex 

 is the n. accessorius of higher vertebrates. 



