left radix aortae 

 internal vessel 

 glomerular rate 

 skeleton 

 -solenocytes protruding through arterial sinus 



outline of coelom 

 coelomic vessel 

 solenocytic vesicle 



B 



septum 

 external vessel 



coelom 



-N.tongue bar 

 ^synapticulor vessel 



left radix aortae 



arterial sinus 



pharynx 



rnal blood vesse 

 skeleton 



cuticle 

 dorsal fin ray 

 sclerocoel 



internal vessel 



ventral nerve 



cavity of pharynx 



tongue bar. 

 septum. 



endostyle 



ventral segmental artery 



^atrial lining 



anterior cardinal vein 



cavity of gonad 

 transverse muscle 

 coelom 

 .ventral body wall 



external vessel. 



skeleton 



synapticula 



coelomic vesse 



septal coelom 



, , -vs-irw I ^^-cy^ mesenchyme 

 coelom ^-sa^ra-t— ^i'7-' 



eridostylor skeletal plates 

 endostylar blood vessel 

 dorsal canal with chordal corpuscles 

 notochord sheath 

 epibranchiol groove 



right radix aortae 

 .subchordal coelom 



solenocytes 

 arterial sinus 

 atrial pouch 



hepatic diverticulum on right side 



gonad 



anterior cardinal 



coelomic cavities 

 metapleural fold 



tongue bar 



septum 



ciliary band 

 internal blood vessel 



Figure 1-4. Anatomical details of Amphioxus. (After Franz) A, cross section of posterior pharyngeal 

 region; B, cross section of endostyle; C, frontal section of pharyngeal bars; D, lateral view of a 

 solenocytic vesicle (after Goodrich, and Franz); E, cross section of a solenocytic vesicle showing its 

 relationship to the blood, coelom, and pharynx; F, cross section of a gonad. 



THE PROTOCHORDATES 



