330 Journal of Comparative Neurology. 



gHon of the trigeminus in the duck there can be demonstrated 

 a very considerable participation of the epidermis. In the 

 chick with nine to ten protovertebrse, we see the root-borders 

 reach the dorsal border of the mesoderm. Duck embryos 

 with eleven to twelve protovertebrfe show the ganglion of 

 the trigeminus in connection with a lateral swelling of the 

 epidermis. Somewhat later the connection with the epi- 

 branchial ganglion appears. In the daw with twelve proto- 

 vertebrre I saw a branchial nerve connected with the epi- 

 dermis in both places at the same time. 



You will grant that it would be altogether premature for 

 me to express an opinion now, more or less probable, upon 

 the changes which the scheme of the nerves of the head of 

 vertebrates here presented experiences up to the completion 

 of development. The reductions, fusions, solutions of con- 

 tinuity and secondary connections appear to vary according 

 to the class in very many ways. 



A comparison of the representation of the branchial nerv- 

 ous system in the AmmoccEtes (Fig. 8) of 4 mm. with a 

 diagram of the cranial nerves of the adult (Fig. 11) shows 

 you how important these changes may be. I have constructed 

 this diagram after Ahlborn's and Julin's drawings, taking 

 into consideration also the statements of Max Fiirbringer and 

 Wiedersheim. To present a better general view, the oculo- 

 motor nerves and hypoglossus are omitted. 



The whole anterior portion of the epibranchial cord, 

 cephalad of the vagus, appears to have appeared, but is still 

 represented by the ramus recurrens and ramus anterior of the 

 facialis. The latter, behind and under the eye, possesses the 

 spindle-shaped ganglion discovered by M. Fiirbringer. I 

 conjecture this ganglion to be the remant of the foremost 

 epibranchial ganglion or a complex of such ganglia. One 

 might express it in this way: That in the course of develop- 

 ment the facialis annexes all those portions of the epi- 

 branchial cord lying cephalad of the vagus. Whether the 



