Plate X. 



Edrioaster bigsbiji. Specimen A, from drawings made in 1899 by Mr. Gilbert C. 

 Chubb. 



Fig. 1. Adoral face. Towards the observer is the posterior interradius, 

 in which are seen the anus and the hydropore. The dark triangular 

 depression between those structures is due to fracture of the plates. 

 X 2 diam. 



Fig. 2. Posterior view, x 2 diam. 



Fig. 3. Adapical face, the posterior interradius being away from the 

 observer, x 2 diam. 



Fig. 4. Some of the floor-plates, showing the groove that leads from 

 the poral depression to the main radial channel. The depression for the 

 cover-plates is not clear in this lighting, x 10 diam. 



Fig. 5. A solid section across the food-groove to show the relation of 

 cover-plates to floor-plates ; based mainly on portions of 1. ant. and 1. post, 

 rays, x 5 diam. 



Fig. 6. A transection of the floor-plates, showing their relation to the 

 interradials. The floor-plate on the left is viewed on its sutural surface, 

 which bears the pore-canal. Based on the broken regions of ant. and 

 r. ant. rays, x 5 diam. 



Fig. 7. The hydropore. The adjacent regions of the floor-plates show 

 the depression that receives the ends of the cover plates, x 10 diam. 



Fig. 8. Parts of the floor-plates and cover-plates near the peristome, 

 showing the accessory plates, x 10 diam. 



Fig. 9. The periproct. x 8 diam. 



Fig. 10. A section reconstructed along the line a-b in Figs. 1 and 3, 

 showing the approximate thickness of the plates and the relations of the 

 adapical hollow and lobes. Nat. size. 



Fig. 11. Part of the thin, plated integument of the adapical face. The 

 actual plates are not so clearly seen in this specimen as they are in some 

 others (cf. Plate XIV). x 20 diam. 



[1914 124, 125] 



