PLATE IP. 



Asthenosoma hystrix, f. 1-5- 



1. Part of test of young, from actinal side, S.l""- in diam. 



2. Same from abactinal side. 



3. Spine of the same. 



4. Spine of fragment of fig. 5". 



5. Transverse section of same. 



b". Fragment of test of Astlienosoraa hystrix, magnified l^-. 



Diadema setosum, /. 6 - 12. 



6. Young in profile, showing anal tube, 2.4°'"- in diam. 



6«. Pointed tentacles of adult Diadema, in abactinal part of poriferous zone. 



Dorocidaris papillata, /. 7-12. 



7. Young, partly denuded, from abactinal side, 2.4'«»- in diam. 



8. Abactinal system of same, showing mode of growth of coronal plates. 



9. Plates of buccal membrane, showing continuation of the poriferous zone, of same. 



10. Magnified spine of buccal membrane of same, showing mode of articuhition. 



11. Buccal membrane, nat. size, of larger specimen. 



12. Edge of two buccal plates of large specimen, with spines and pores magnified. 



Cidaris tribuloides, /. 13, IS''- 



13. Young specimen, from abactinal side, 5.4"°' in diam. 



13"- Actinal membrane of adult, showing continuation of poriferous zone and tentacles 

 from the edge of test to the teeth. 



Coelopleurus floridanus, /. 7^, 15. 



14. Restored spine of Coelopleurus, nat. size. 



15. Transverse section of same, magnified. 



