i8o 



STRONG. 



[Vol. X. 



in which they have been studied and carefully distinguished. 

 The agreement between the larval forms of Anura and the 

 fishes is quite remarkable. The same general plan holds for 

 both. It is owing principally to the labors of Allis and Ewart 

 that this general plan has been made clear in fishes. As in the 

 latter forms many variations are found, such, doubtless, will be 

 found the case also in amphibian larvae and in Urodela, both in 

 the arrangement of the organs and the courses and smaller 

 ramifications of their nerve supply; but the roots and principal 

 divisions and their arrangement will probably be found to hold 

 good for all. 



One very important difference, apparently, between the con- 

 ditions in fishes and Amphibia, has emerged however ; and 

 this relates to root No. 3. The question of the fate of this 

 root can be most conveniently considered with the next com- 

 ponent, though in many respects it falls most properly under 

 the component just discussed. 



3. Fasciculus Communis. 



a. Amphibia. — The third component is, as has been de- 

 scribed, derived from the fasciculus communis. 



Table. 



Preauditory — 

 one root (gang.) 



Fasciculus communis 

 (+ adjoining nu- -; 

 cleus ?). 



Postauditory — 

 several roots (gang.) 



f R. palatinus — roof of phar)mx. 

 -{ R. mandibularis — portion of 

 (^ floor of pharynx. 



R. lingualis IX — part of floor 



of pharynx. 

 Rr. pharyngei — pharynx and 



part of filtering apparatus. 

 ■^ Rr. branchiales — gills, part 



of filtering apparatus and 



pharynx. 

 R. visceralis — heart, lungs, 



oesophagus, etc. 



This remarkable tract appears in transverse sections of that 

 part of the medulla of the tadpole just cephalad of the opening 

 of the fourth ventricle, as an oval island, as it were, imbedded 



