Plate 113. 

 1. Strongylocentrotus echinoides A. Ag. and CI. 



1. Side view of partly denuded specimen. 



2. Strongylocentrotus polyacanthus A. Ag. and CI. 



2. Side view of type-specimen, partly denuded. 



3-6. Strongylocentrotus fragilis Jackson. ^ 



3. Side view of type-specimen; test broken, showing auricles. 



4. Abactinal view of same. 



5. Side view of a smaller specimen. 



6. Abactinal view of same. 



All figures natural size. 



I 



I 



