PLATE LVII. 



PAGE 



Figs. 1-7. Acanthasciis cactus, F. E. S., . . .148 



Fig, 1. A dried specimen ; natural size. 



Fig. 2. Spicules of a section perpendicular to the outer surface, in natural 

 position (combination figure) ; x 20. 



Fig. 3. Oxyhexaster with long, bent, terminal rays ; x 300. 



Fig. 4. Discohexaster with some superumerary accessory radial thorns ; x 300. 



Fig. 5. Spicules with six normal and two accessory rays ; x 300. 



Fig. 6. Autodermal tetract with straight, rough, rounded rays ; x 300. 



Fig. 7. Autodermal pentact with straight, rough, rounded rays ; x 300. 



Figs. 8-13. Acanthascus dubius, F. E. S., . . 147 



Fig. 8. Oxyhexaster with long, bent, smooth terminal rays ; x 300. 



Fig. 9. Discohexaster with several S-shaped terminal rays on each principal ; 

 x450. 



Fig. 10. Discohexaster with three terminal rays on each principal ; x 450. 



Fig. 11. Discohexaster with numerous terminal rays on each principal ; x 450. 



Fig. 12. Long parenchymal- diacts bound together by numerous transverse synap- 

 ticula; x 100. 



Fig. 13. Oxyhexact with long, straight, smooth rays, and a tuberculate central 

 node ; x 300. 



