KXOGYRA. 415 



? 1870. OsTREA coLUMBA, W. A. Oonter. Protozoe Helvet., vol. ii, p. 57, pi. x, 



fig. 18. 

 — ExoGYKA coLUMBA, F. Bi'imei: Geol. v. Oberschles., p. 332, pi. xxvi, fig. 1. 



1871. OsTRKA COLUMBA, F. J. Piclet and G. Camjnche. Foss. Terr. Crt't. Ste. 



Croix (Matt'r. Pal. 



Suisse, ser. 5), p. 319. 



■ — ExoGYRA suBORBicDLATA, F. StoUczka. PaliBout. Iiidica, Cret. Foss. S. 



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

 xxxv, figs. 1 — 4. 



1872. OsTREA (Exogyra) colujiba, H. B. Geinitz. Das Elbtbalgeb. in Sachsen 



(Palaeontographica, vol. 

 XX, pt. 1), p. 181, \<\. xl, 

 figs. 4 — 7. 



1877. ExoavRA col,v:!.iba, A. Fritscli. Stud, ini Gebieteder bobm. Kreidefoiinat., 



ii. Weissenberg. u. Malnitz. Sehicbt., 

 p. 139, fig. 135. 



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



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

 1882. Exogyra ratisbonensis, G. Seguenm. Atti R. Acead. Liucei, ser. 3, CI. 



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

 pi. xix, fig. 1. 

 1890-91. OsTREA suBORBicuLATA, A. PeroH. Descript. Braeh. etc., Terr. Crt't. 



Tuuisie, p. 119. pi. xxiii, figs. 

 11—13. 

 1893. OsTREA COLUMBA, S. Meutiier. Le Naturaliste, p. 176, fig. 3. 

 — Exogyra columba, R. Michael. Zeitscbr. d. deutscb. geol. Gesellscb., 



vol. xlv, p. 238. 

 y — _ svBOit.Bicvi..KT\, T. W. Stanton. Colorado Formation (Bull. U.S. 



Geol. Survey, No. 106), p. 

 62, pi. V, fig. 6 ; pi. vi, fige. 1, 

 2 ; pi. viii, fig. 1. 

 1897. — COLUMBA, R. Leonhanl. Palaeoutograpbica, vol. xliv, p. 27. 



_ _ — V. Sohle. Geogn. Jahresb. (1896),p. 41. 



9 1900. — — G. Mailer. Deutscb-Ost-Afrika, vol. vii, p. 566, pi. 



xxiv, fig. 2. 



1902. — P. Ojtpenhehn. CentralM. fiir Min., t'tc., p. 500. 



1903. OsTREA SUBORBICULATA, R. Fortau. Bull. Inst, flgjptieu, ser. 4, vol. iv, 



p. 289. 

 1911. Exogyra columba, 0. Schlagintweit. Neues Jabrb. fiir Miu., etc., Beil.- 



Bd. xxxiii, ]>. 111. 



Deacnptioii.—HlxeW very inequivalve, moderately or rather considerably inecpii- 

 lateral, iisnally higher than long and more or le.ss 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 



