Plate XII. 



Edrioaster levis. Holotype (Brit. Mus., E 15900). x 2 diam. These photo- 

 graphs were taken under water, so as to bring up the sutures and the 

 fragments of plates, which are seen with much difficulty in the dry state. 



Fig. 1. Adoral face. The small periproctals are seen depressed in the 

 posterior interradius, next the observer. 



Fig. 2. Adapical face. This shows the peripheral course of the 

 grooves. The frame and the plated integument within it cannot be 

 distinguished. 



[1914 125] 



