Bull. U. S. F. C. 1902. 
Plate 9. 
Figs. 53-57. Strongylocentrotus drobachiensis (natural size). — 53. Aboral view of test with spines. 54. Oral view of test with 
spines. 55. Side view of test without spines. 56. Aboral view of test without spines. 57. Oral view of test without 
spines. 
