Plate 51. 



1, 2. Diadema pauciBpinum A. Ag. 



1. Valve of large tridentate pedicellaria. x 70. 



2. Part of margiu of same, seen from side, x 70. 



3-11. Centrostephanus asteriscus A. Ag. and CI. 



3. Sleuder tridentate pedicellaria. X 70. 



4. Stout tridentate pedicellaria. X 70. 



6. Large ophicephalous pedicellaria without glands. X 70. 



6. Ophicephalous pedicellaria with glands. X 70. 



7. Triphyllous pedicellaria. X 70. 



8. Globiferous pedicellaria. X 70. 



9. Side view of valve of globiferous pedicellaria. X 70. 



10. Interior view of base of same. X 70. 



11. Calcareous particles from pedicels, x 70. 



12-20. Centrostephanus coronatus A. Ag. 



12. Slender tridentate pedicellaria. x 70. 



13. Stout tridentate pedicellaria. x 70 



14. Ophicephalous pedicellaria. X 70. 



15. Triphyllous pedicellaria. X 70. 



16. Globiferous pedicellaria. X 70. 



17. Globiferous pedicellaria with glands on stalk. X 70. 



18. Side view of valve of globiferous pedicellaria. X 70. 



19. Interior view of base of same. X 70. 



20. Upper end of stalk of globiferous pedicellaria. X 70. 



