Plate XX. 



Fig. I. Tridentate pedicellaria of Echinus Alexandri. Obj. o. Oc. I. 



— 2. Spictiles of Echinus Alexandri. Obj. V. Oc. I. 



— 3. \'alve of a tripli\llon.s pedicellaria of Strongylocentrotus drebachiejisis. Obj. II. Oc. III. 



— 4. _ — tridentate — - — — i.graji/i/atus. Obj.o. Oc. I. 



— 5. — — ophicephaloiis — - — — Obj. II. Oc. III. 



— 6. — — tridentate — - — — Obj. o. Oc. I. 



— J. — — triphvllous — - Sterechimis Neumayeyi. Obj. II. Oc. III. 



— 8. Spicules of Echinus elegans. Obj. V. Oc. I. 



— 9. Tridentate pedicellaria, small form, of Echinus elegans. Obj. II. Oc. o. 



— 10. Valve of a tridentate pedicellaria of Strongylocentrotus pulcherrinttis. Obj. II. Oc. o. 



— II. Tridentate pedicellaria of Sterechimis Netimayeri. Obj.o. Oc. I. 



— 12. Spicules of Strongylocentrotus drebachiensis. Obj. V. Oc. I. 



— 13. Sphceridia of — — Obj. II. Oc. III. 



— 14. Valve of a globiferous pedicellaria of Strongylocentrotus purpuratus, from the inside. Obj. II. Oc.o. 



— 15. Globiferous pedicellaria of Psammechinus var/egatus. Obj. II. Oc.o. The skin full of spicules. 



— 16. Valve of a globiferous pedicellaria of Strongylocentrotus drebachiensis , from the in.side. 



Obj. II. Oc. I. 



— 17. Spicules of Echinus a/finis. Obj. V. Oc. I. 



— 18. vSphaeridia of Strongylocentrotus drobachiensis. Obj. II. Oc. III. 



— 19. Tridentate pedicellaria, large form, of Echinus elegans. Obj. o. Oc. o. 



— 20. Valve of a tridentate pedicellaria of Strongylocentrotus drebachiensis. Obj. o. Oc. I. 



— 21. — — triphvllous — - Echinus a/finis. Obj. II. Oc. III. 



— 22. — — — — - — elegans. Obj. II. Oc. III. 



— 23. Stalk of a globiferous pedicellaria of Echinus elegans. Obj. II. Oc. I. 



— 24. Spine from the buccal plates of Echijius esculentus. Obj.o. Oc.o. 



— 25. Globiferous pedicellaria, the neck protrtided, of Strongylocentrotus drebachiensis. The sjjicules 



are drawn onl\- on the upper side of the head. Obj. o. Oc. I. 



— 26. \'alveofa ^oh\lQXo\\¥<Y'^^'^z(A\7\.x\7}ioi Strongylocentroizis dr0bachie72sis^ from the side. Ohj.II. Oc. I. 



— 27. — — ophicephalous — large form, of Echinus Alexandri. Obj. II. Oc. o. 



— 28. — — globiferous — oi Strongylocentrotzts purpuratus, ixom the siAt. Obj. II. Oc.o. 



— 29. Cilobiferous pedicellaria, the neck retracted, of Strotigyloc. drebachicnsis. Obj. o. Oc. III. 



— 30. Spine of Echinits esculentus., the basal part. Obj. o. Oc. o. 



