ASTERIAS FORBESI 



177 



___:ves.ped. 



cn.hy. 



org.ax.__ 

 sin.ax. 



FIG. 34. Ambulacral system of a starfish after Delage and Herouard. 

 lac. ann, oral lacuna; en. ann, oral (ring) canal (ambulacral) ; sin. o, oral 

 sinus; sin. rd, radial sinus; en. rd, radial canal (ambulacral); lac. rd, radial 

 lacuna; en. hy, hydrophone (stone) canal; org. ax, axial organ; sin. ax, axial 

 sinus; en. /, transverse canal; v, valve between transverse canal and ampulla; 

 ves. pol, polian vesicle; en. pdb, ambulacral tube; ves. ped, ampulla; en. pd, 

 sucker. 



radius of the hydrophone canal) which are minute glands pro- 

 ducing amcebocytes. The ring canal gives rise to five radial 

 canals each of which runs imbedded in the body wall along the 

 median line on the ventral surface of the arm ending blindly in 

 the terminal tentacle just before the last ossicle. Each radial 

 canal gives off at regular intervals transverse canals. Each pair 

 of transverse canals consists of a short canal on one side and a 



