PLATE p. 



Cidaris Thouarsii, f. 1- 5*. 



1. Large interamlnilacral spine, very coarse granulation. 

 1°. Tip of spine of Fig. 1 seen endways. 



2. Somewhat smaller interambulacral spine, granulation less distinct than in Fig. 1. 



3. Pointed interambulacral spine, nearly smooth. 



4. Pointed interambulacral spine near actinostome. 



5. One of the flat triangular papillce (anibulacral spines). 

 5". Part of test, nat. size. 



5*. Part of test of older specimen, showing the broad bare median interainbidacral space. 



Goniocidaria canaliculata, f.G- S''. 

 6 - 8*. Interambulacral spines. 



Goniocidaria tubaria, f. 9 - 14. 



9, 10. Large abactinal interambulacral cupuliform spines. 

 11, 12. Smaller interambulacral actinal spines. 



13. Large, pointed interamliulacral abactinal spine. 



13". Lai-ge, cupuliform, spiny interambulacral abactinal spine magnified. 



14. Smooth, pointed interambulacral abactinal spine. 



Goniocidaria geranioides, /. 15-17. 

 Three different kinds of abactinal interambulacral spines. 



Cidaria tribuloidea, /. 18-22. 



18. Large, coarsely granular abactinal interambulacral spine. 

 18°. Tip of Fig. 18 magnified, in profile. 



18*. Tip of Fig. 18 magnified, end view. 



19. Smaller, pointed, and less granular abactinal spine. 



20. Smaller, smooth, pointed abactinal spine. 



21. Short, actinal, slightly granular spine. 



22. Large, pointed, .smooth abactinal spine. 



Cidaria metularia, /. 23-24''. 



23. Large abactmal fluted spine. 



23°, 23''. Profile and end view of same magnified. 



24. Small, short, coarsely granular actinal spine. 

 24", 24''. Profile and end view of same magnified. 



Dorocidaris papillata, /. 25-33. 



25. Large, pointed abactinal interambulacral spine. 



26. Somewhat smaller, less distinctly seiTated spine. 



27. Small, pointed interambulacral spine near ambitus, with sharp serrations. 

 25°, 26*, 27°. Magnified parts of Figs. 25, 26, 27, to show serration. 



28. Small, short actinal interambulacral spine. 



Figs. 25 - 28 from the Meiliterranean. 



29. 30, 31. Different, smooth, abactinal interambulacral spines. 



32, 33. Flat, short, actinal interambulacral spines, with serrated edges. 

 Figs. 29 - 33, Florida Straits. 



