230 Christmas Island. 



Orbitnlites dispansa (Sow.), d'Archiac, 1850, Histoire progres Geologic, 

 *' Tableau de la Faune nummulitique," vol. iii, p. 230. 



lyeophris disjoansus, Sow., Carter, 1853, Ann. Mag. Nat. Hist., ser. ii, vol. xi, 

 p. 172, pi. vii, figs. 23-29 ; (1853), Journ. Bombay Br. R. Asiatic 

 Soc, vol. V, pt. 18, p. 136, pi. ii, figs. 23-29 ; 1857, Geol. Papers 

 Western India, p. 451, pi. xviii, figs. 16, 16«, 16i, and p. 545, 

 pi. xxiii, figs. 23-29. 



Orbitoides dispansa (Sow.), Carter, 1861, Ann. Mag. Nat. Hist., ser. iii, vol. viii, 

 p. 447, pi. xvi, fig. 1 ; pi. xvii, fig. 1. 



Orbitoides {BiscocycUna) dispansa (Sow.), Giimbel, 1868 (1870), Abhandl. 

 m.-ph. CI. k. bayer. Ak. Wiss., vol. x, p. 701, pi. iii, figs. 40-47. 



Orbitoides dispansa (Sow.), Hantken, 1871, A magy. kir. foldt. int. evkonyve, 

 vol. X, p. 132, pi. ii, figs. Ida, b ; and Mitth. Jahrb. k. ungar. 

 geol. Anstalt, vol. i, p. 138, pi. ii, figs. 10^, b ; Brady, 1875, 

 Geol. Mag., dec. ii, vol. ii, p. 536, pi. xiv, figs. 2a, b, c; 

 Hantken, 1875 (1876), A magy. kir. foldt. int. evkonyve, vol. iv, 

 p. 72, pi. xi, fig. 3 ; and Mitth. Jahrb. k. ungar. geol. Anstalt, 

 vol. iv, 1875 (1881), p. 82, pi. xi, fig. 3; Fritsch, 1878, 

 Palseontographica, Suppl. iii, Lief, i, p. 142, pi. xviii, fig. 10 ; 

 pi. xix, fig. 8 ; Brady, 1878, Jahrb. Mijn. Ned. Oost-Indie, 

 vol. vii, pt. 2, p. 164, pi. ii, figs. 2a-c ; Medlicott & Blanford, 

 1879, Geol. India, pp. 340 and 459, pi. xv, fig. 8. 



Orbitoides [BiscocycUna) dispansa (Sow.), Biitschli, 1880, in Bronn, Klassen, 

 etc., Thier-Reichs, p. 215, pi. xii, fig. 16. 



Orbitoides dispansa (Sow.), Martin, 1881, Samral. geol. Reichs-Mus. Leiden [I], 

 vol. i. Heft 2, p. 112, pi. vi, figs. 1-3. 



Orbitoides [BiscocycUna) dispansa (Sow.), Jennings, 1888, Geol. Mag., dec. iii, 

 vol. V, p. 530, pi. xiv, fig. 6. 



Orbitoides dispansa (Sow.), Verbeek, 1891, ''Voorloopig Bericht over Nummu- 

 lieten, Orbitoiden, en Alveolinen van Java," Nat. Tijdschr. v. 

 Nederl. -Indie, vol. Ii, p. 120, figs. 9«, b ; Yerbeek & Fennema, 

 1896, '* Descr. geol. Java et Madoura," vol. i, pl. ix, figs. 

 148, 149; pl. X, figs. 158-160; vol. ii, p. 1173. 



It lias been noticed by previous authors, who have described 

 Orbitoides from the Eastern Archipelago and India, that the older 

 strata comprising the Eocene and Oligocene are characterized by 

 the type of Orhitoides limited by the subgenus Discocyclina^ which 

 has the chambers of the median plane of a rectangular shape ; 

 whilst the Miocene strata yield Orhitoides of the subgeneric type 

 Lepidocyclina, which has the median chambers lozenge-shaped or 

 subcircular. 



The present section (No. 2) shows a few examples of Orhitoides 

 somewhat fractured on the flanged portion. Some of these frag- 

 ments of the flange are turned in upon the plane of section, thus 

 accurately showing the shape of the median chambers, and 

 conclusively prove the affinity of the present species to the 

 Discocyclince. -Special attention is di'awn to this occurrence, since 

 the great mass of the Orbitoidal Limestone of Christmas Island 

 is composed of Lepidocyclince, and are therefore presumably of 

 Miocene age, whilst these now mentioned are possibly of Upper 

 Eocene or Oligocene age. 



