original descriptionSpencer, W. K. (1914). The Evolution of the Cretaceous Asteroidea. <em>Philosophical Transactions of the Royal Society B: Biological Sciences.</em> 204(303-312): 99-177., available online athttps://royalsocietypublishing.org/doi/pdf/10.1098/rstb.1914.0004 page(s): 122 [details]