PLATE V*. 



Strongylocentrotus franciscanus, /. 7, f. 



1. Seen from the abactinal side, j nat. size. 



2. Same from the actinostome, | nat. size. 



Strongylocentrotus lividns, /. 3. 



3. Seen from the abactinal side. 



Strongylocentrolnis tuberculatus, /'. ^, 5. 



4. Seen from the actinal side. 



5. Seen from the abactinal side. 



{Figs. 3-5 ludural six.) 



