Fig. 2Za. 



Phjtzrvnjc 



%a/>^Joimi.,M£^ScoM.4fJSM4S. 



-^^J 



J^i0- 22 b 





CoUarcavi^ 



Atrial ihickena^ 



Fur 23 a.. ^'¥o" 



Ficf. 25. 



Pkarjnjc 



Fia, 2Z c. 



Pkouyruc 



Fvc/.Zd b. 



Figr. 2^. 



AtriaZ ccwity 

 Collar cavLtj m, AtrialfolcLs 



// Artcfaci 



Fi^.2y. 



CavUyofMtlafleura i ^ 

 = Collar caviO^ 



AirioZ cavdy 



^^2^^^^^^^^^2^^^C^^^^^ 



AMPHIOXUS. 



Proboscis cavity 

 ■-•ColloLr cavUy 



TriLnlc cavLly 



TrurtJcBody ccu/ily 

 Fi^. 2S. 



Huicl ccu/Uy 



Collar couvUy 



BALANOGLOSSUS. TriuikcmUf 



BALANO G LOSSUS. 



Collar cccvity Proboscis oavily 



FHutli.liili'Edin' 



