Exogyraは、白亜紀に北米からヨーロッパ、北アフリカ、西アジアに分布したカキの仲間。 Exogyra (f.) Say, 1820, 2(1): 43, type species (M) Exogyra costata Say, 1820, 2(1): 43; Gryphaeidae. New Lat. exo-, from Gr. exw; Gr. gyros, round, a ring, circle (Liddell & Scott, 1955), or Lat. gyrosus, adj. A, curved backwards and forewards in turn, spiral (Stearn, 1983). 輪、円の外、或は外側へ螺旋状に曲がる(もの);ベッコウガキ科歪嘴蛎属 Exogyra costata Say, 1820 sensu Stephenson, 1914, pl. 19, figs. 1-4. Exogyra costata Say, 1820 sensu Stephenson, 1914, pl. 20, fig. 1.
Say, Thomas, 1820. Observations on some species of zoophytes, shells, &c. principally fossil. The American Journal of Science, and Arts, vol. 2, no. 1: 34-45. [Exogyra: 43; available online at https://www.biodiversitylibrary.org/item/51607#page/1/mode/1up] Stephenson, Lloyd William, 1914. Cretaceous deposits of the eastern Gulf region and species of Exogyra from the eastern Gulf region and the Carolinas. United States Geological Survey, Professional Paper 81: 1-77, pls. 1-21. [available online at https://www.biodiversitylibrary.org/item/124946#page/11/mode/1up]