PLATE Y. 



HoLOPUS RANGi, d'Orbigiiy. 



Fig. 1. The articular facets of the radials viewed from above, . x 



Fig. 2. Horizontal section of the radials, 2 mm. below the edges of 

 the two bivial facets. This is an inferior view of the ring 

 of united radials shown in fig. 1 , . . . x 



Fig. 3. Vertical section through the lower part of the cup, . . x 



Fig. 4. Horizontal section through the lower part of the cup, about 



5 mm. above the basal expansion, . . . x 



Fig. 5. The calcareous network forming the peripheral portion of the 



cup, . . . . . . .X 



Fig. 6. The calcareous network forming the inner faces of the radials, x 



Fig. 7. Portion of a horizontal section through the cup, showing the 



relations of the two kinds of network, . . . x 



Fig. 8. Ideal representation of the more regular network forming the 



outside of the cup, . . . . . x 



Figs. 9, 10. The youngest individual dredged by the "Blake,". x 



Fig. 9. From the side. 

 Fig. 10. From above. 



Diam. Page 

 3 202 



3 



9 



200 

 201 



200 



