basis of recordBlake, D.B. and Zinsmeister, W.J. (1988). Eocene asteroids (Echinodermata) from Seymour Island, Antarctic Peninsula. <em>Geological Society of America Memoir.</em> 169: 489-498., available online athttp://memoirs.gsapubs.org/content/169/489.short page(s): 494 [details]