1. Faure-Fremiet, Mem. Mus. Roy. Hist. Nat. de Belgique, 3, 1134 (1936).
2. Kahl, "Tierwelt der Nord- und Ostsee", 23 (2), 93 (1933).
3. Andrews, J. Mar. Res. Sears Foundation, 5 (3), 169 (1944).
4. Kent, "A Manual of Infusoria", 2, 599 (1880–82).
5. Orton, J. Mar. Biol. Assoc., 16, 379 (1930).