Plate 15. 



Stereocidaris leueacantha A. Ag. and Clark. 



1. Abactinal view of medium-sized specimen. 



2. Actinal view of same. 



3. Ainbulacral view of partly cleaned specimen. 



4. Interambulacral view of same. 



Other views of specimen shown in figs. 3 and 4 will be found on Plate 32, figs. 5 and 6. 



All figures natural size. 



