Published in Biol Bull, in 1958, in volume 114, pages 226-246
Created: 2010-01-06, modified: 2011-06-21
doi:10.2307/1538851
Published in Biol Bull, in 1989, in volume 176, pages 301-307
Created: 2010-01-07, modified: 2011-06-21
doi:10.2307/1541988