FIG. 63. Diagrams of Tunicate (on the left), Amphioxus (centre), and young Lamprey (right). 



Mouth ; au, eye ; c, peribranchial chamber ; c/i, notochord ; if, alimentary canal ; g, ear ; /<z, heart ; k, gills ; li>, live 

 m, nerve cord ; /, brain ; ing, stomach ; mt, mantle ; *, tunicate embryos. 



