PLATE XIII". 



Echinarachnius exoentricus, /. i - 4- 



1. Interior view, the abactinal floor removed, | nat. size. 



2. Interior view, the actinal floor removed, | nat. size. 



3. Seen from the abactinal pole, | nat. size. 



4. Seen from the actinal side, | nat. size. 



Echinarachnius mirabilis, /. 5, 6. 



5. Part of the abactinal floor removed to show the structure of the lower floor, nat. size. 



6. Seen from the actinal side, nat. size. 



