PLATE y-. 



Strougylocentrotus armiger, /. /. 



1. Seuu in pi'iifilf. 



Strongylocentrotus euiythrogranimus, /. '^-4- 



2. Seen in luufile. 



3. Seen from actinnl side. 



4. Seen frum tlie alwetinal pule. 



Strongylocentrotus purpuratus, /. ,*, G. 



0. Seen from aliactinal side. 

 (i. Seen I'runi the actinal side. 



Sphaerechinus granulans, /. 7. 



7. Seen from the aliactinal pole, j nat. size. 



Pseudoboletia Indiana, /. S, 9. 



8. Seen from the actinal side. 



9. Seen from the abactinal pcde. 



Echinostrephus molare, /. 10-12. 



1(1. Seen from the actinal side. 



1 1 . Same in profile. 



12. Seen from the aliactinal side. 



(.4// J^iV/s., ein'pf 7, 'nninnd xhe.) 



