nerve 



norocbord 



otriopore 



inresTine 



central canal 



cior6al aorta 



hyperbranchial qroovje 



bQpaTic vein 



qill bar 

 qill slit 



hypobranchiol 

 qroove 



ventral aorta 



epidermis 

 dermis 



metapleural 

 ibid 



Fig. 13-8. Amphioxus in longitudinal and cross-sections. 



