Fig, 11 End twig of terminal nerve with ganglion cells and peripheral fibrils 



Fig. 12 Ventral view of snout and mouth of Amphioxus, to illustrate rela- 

 tions of brain to anterior buccal pouch, and the distribution of the terminal 

 and septal nerves as seen from below. The hypophysial organ with dorsal 

 buccal groove running caudad and the band of thickened epithelium running 

 cephalad are shown. In the drawing the head is expanded laterally to make 

 room to show the parts clearly. 



Fig. 13 Sagittal section of brain and nasal organs of Ammocoetes, to show 

 relations of olfactory and terminal nerves to the brain and the olfactory and 

 terminal organs. 



Fig. 14 Horizontal section of brain and nasal organs of Ammocoetes, to 

 show relations of olfactory and terminal nerves and the nasal septum. 



Fig. 15 Three cells from the 'nasal' epithelium of Ammocoetes, one olfactive 

 sense cell and two ciliated epithelium cells from the ciliated 'gland' of the ter- 

 minal organ. 



.Fig. 16 Part of a section of the 'gland' of the terminal organ. 



330 



