PLATE XIII^ 



Echinodiscus auritus, f. 1-3. 



1. Seen from al)Ove, | nat. size. 



2. Seen from below, | nat. size. 



3. Part of abactinal floor removed to show the internal structure, | nat. size. 



Hotula Augusti, /. 4, 5. 



4. Seen from the actinal side. 



5. Same seen from the abuctinal side. 



Rotula Rumphii, /. 6, 7. 



6. Seen from the abactinal side. 



7. Seen from the actinal side. 



{Figs. 4-7 natural size.) 



