From a three square meter plot of intertidal shore on a rocky point of York, Maine, sea urchins (Strongylocentrotus droebachiensis) were collected on June 28 and 29, 1957 for study of their size-frequency distribution. Test height, test weight, number of wedges in the spines, number of pore-pairs in the ambulacral arcs, number of ocular plates insert, and number of coronal plates have been related to test diameter....
Swan, Emery F.. 1958. "Growth and variation in sea urchins of York, Maine." Journal of Marine Research 17, (1). https://elischolar.library.yale.edu/journal_of_marine_research/938