Michael J. Bok, María Capa, Dan-Eric Nilsson, Here, There and Everywhere: The Radiolar Eyes of Fan Worms (Annelida, Sabellidae), Integrative and Comparative Biology, Volume 56, Issue 5, November 2016,
Presence (+) and absence (-) of pneumatic characters found on the caudal vertebrae from specimens of the 11 taxa studied. The penguin with the pneumatised vertebrae is Pygoscelis papua (NHMUK unregist
