Fig. 1 View of left side of the head of Amphioxus, showing brain and nerves 

 The terminalis, opticus, olfactorius, and septalis are the first four cranial nerves. 

 The apical territory supplied by the terminal and septal nerves is distinctly 

 marked off from the rest of the head and its close association with the optic and 

 olfactory sensory structures is evident. The septal territory has already under- 

 gone partial migration into the buccal cavity. The path of migration of the 

 hypophysial organ is indicated by the letters A and B and the dotted line B-C. 

 Over the outline of the apical buccal pouch is shown the last surface position (in 

 the larva) of the pre-oral pit (hypophysial organ) before its entrance into the 

 mouth chamber. 



Fig. 2 Anterolateral view of the brain of Amphioxus (short type), showing 

 the terminal, septal, and olfactory nerves and the region of the lamina terminalis. 



Fig. 3 Anterior view of the same brain of Amphioxus. 



Fig. 4 Ventrolateral view of the same brain of Amphioxus, showing the first 

 three nerves and the infundibular territory. 



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