EXOGYRA. 415 



? 1870. Ostrea columba, W. A. Ooster. Piotozoe Helvet., vol. ii, p. 57, pi. x, 



fig. 18. 

 Exogyra columba, F. Bomer. Geol. v. Oberschles., p. 332, pi. xxvi, fig. 1. 



1871. Ostrea columba, F. J. Piclet and G. Campiche. Foss. Terr. Oct. Ste. 



Croix (Mater. Pal. 

 Suisse, ser. 5), p. 319. 



— Exogyra suborbiculata, F. Stoliczka. Palseont. Indica, Cret. Foss. S. 



India, vol. iii, p. 462, pi. 

 xxxv, figs. 1 — 4. 



1872. Ostrea (Exogyra) columba, H. B. Geinitz. Das Elbtbalgeb. in Sachsen 



(Palseontographica, vol. 

 xx, pt. 1), p. 181, pi. xl, 

 figs. 4—7. 



1877. Exogyra columba, A. Fritsch. Stud, im Gebieteder b6hm. Krekleformat., 



ii. Weissenberg. u. Malnitz. Scliicht., 

 p. 139, fig. 135. 



1878. Rhynchostreon Chaveri, E.Bayle. Explicat. Carte geol. France, vol. iv, 



Atlas, pt. 1, pi. cxxxviii, figs. 1 — 5. 

 1882. Exogyra ratisbonensis, G. Segttenza. Atti R. Aecad. Lincei, ser. 3, CI. 



Sci. Fis. Math., vol. xii, p. 181, 

 pi. xix, fig. 1. 

 1890-91. Ostrea suborbiculata, A. Peron. Descript. Brach. etc., Terr. Cret. 



Tunisie, p. 119, pi. xxiii, figs. 

 11—13. 

 1893. Ostrea columba, 8. Meunier. Le Naturaliste, p. 176, fig. 3. 



— Exogyra columba, B. Michael. Zeitschr. d. deutsch. geol. G-esellseh., 



vol. xlv, p. 238. 

 ? — suborbiculata, T. W. Stanton. Colorado Formation (Bull. U.S. 



Geol. Survey, No. 106), p. 

 62, pi. v, fig. 6 ; pi. vi, figs. 1, 

 2 ; pi. viii, fig. 1. 

 1897. — columba, B. Leonhard. Palseontographica, vol. xliv, p. 27. 



— V. Sdhle. Geogn. Jahresh. (1896), p. 41. 



? 1900. — G. Mitller. Deutsch-Ost-Afrika, vol. vii, p. 566, pi. 



xxiv, fig. 2. 



1902. — — P. Oppenheim. Centralbl. fur Min., etc., p. 500. 



1903. Ostrea suborbiculata, B. Fortau. Bull. Inst. Egyptien, ser. 4, vol. iv, 



p. 289. 

 1911. Exogyra columba, O. Schlaginhveit. Neues Jahrb. fur Min., etc., Beil.- 



Bd. xxxiii, p. 111. 



Description. — Shell very inequivalve, moderately or rather considerably inequi- 

 lateral, usually higher than long and more or less ovate in outline, with, in some 

 cases, the postero-ventral margin somewhat produced. 



Left valve inflated, usually with a very small surface of attachment. Umbo 

 usually prominent, spiral, curved more or less considerably backwards. The 

 flank of the valve may be regularly convex, or may show a rounded carina 



