regularly t;hirt:;-two of these, sixteen in the radii of the rho- 

 palia, and sixteen interrhopalial. V/hen the number of rhopa- 

 lia is increased the number of radial canals may or may not in- 

 crease in proportion. There are often thirty-four or thirty- 

 six of them. The rhopalial radial canals are larger and more 

 nearly straight than the interrhopalial ones and all are con- 

 nected by a fine net'vork of anastomosing canals, among which 

 no distinct circular canal can be recognized. The meshes in 

 the network of canals are not free from entoderm, for in these 

 areas the entoderm of adjacent canals is connected hy a plate 

 of entodermal cells, the entoderraal lamella. This lamella is 

 also in contact with the subumbrellar ectoderri along a line 

 encircling the umbrella a short distance from its margin, so 

 tliat there is a complete sheet of entoderm separating the ex- 

 umbrellar from the subumbrellar jelly. 



19 



