No. I.] THE CRANIAL NERVES OF AMPHIBIA. 191 



sule, but also to the forward position of the heart and part of 

 the viscera, the courses of these branches are likewise altered. 



It will now be well to discuss the character of the lobus 

 trigemini. It has already been seen that the root from this 

 structure, where best developed, supplies fibres to the various 

 branches of the Facialis, and also independently gives origin 

 to a R. palatinus, R. lateralis, and other recurrent branches. 

 Stannius has already stated {v. stcpra) his belief that this root 

 was concerned largely in the innervation of the terminal buds 

 which are found so abundantly over the surface of the head, 

 gular plate, dorsal part of the body in some cases at least, and 

 in the mouth and gill cavities. Wright has made similar obser- 

 vations as to the innervation of these organs by nerves from 

 this root, especially around and on the barbels where the buds 

 are so concentrated. Whether this root is devoted to the 

 terminal buds as exclusively as those from the tuberculum 

 acusticum are devoted to the canal organs, will require further 

 investigation; that it is largely concerned with the innervation 

 of the buds seems quite certain. 



Stannius is not always clear in his description of this root. 

 In some forms — Spinax and Selachians generally — his fine- 

 fibred root emerges quite ventrally, on a level with the motor 

 root of the VII. We have seen, however, that other investi- 

 gators in Selachians have always described the root from the 

 lobus trigemini as the most dorsal, and that this is its position 

 in Teleosts. From this ventral fine-fibred root of Stannius is 

 derived the R. palatinus. When we consider this, and also that 

 Mayser and Wright do not describe any root of the Facialis 

 derived from the lobus vagi; that Mayser considers the lobus 

 vagi and lobus trigemini to be similar; that the fasciculus 

 communis root of the VII in Amphibia sometimes emerges dor- 

 sal and sometimes ventral to the VIII (though always ventral to 

 the lateral-line root) ; and that there is apparently in Amphibia 

 no lobus trigemini root, it would seem not improbable that we 

 were really dealing here with the same root, which simply 

 shifted its position. On the other hand, as we have just seen, 

 while Stannius describes this fine-fibred root as rather ventral in 

 Selachians, others find in Selachians a dorsal root arising typic- 



