NERVOUS SYSTEM OF VERTEBRATES. 



downward in front of the gill slit. It has been suggested that 

 the epibranchial placodes represent ancestral sense organs whose 



Vagus root gong, 



Accessory root gang. 



7X root gang. 



Gong, petros. 

 N tymp 



Br to 

 carotid plexus 



Froriep 



Sympathetic. 



FIG. 32. Reconstruction of the peripheral nerves in a six weeks human embryo, 

 17. 5 mm. long. From Streeter. 



