ORTMANN : TERTIARY INVERTEBRATES. 99 



Remarks : Characterized by the well developed radial plaits, and by the 

 deeply and regularly excavated lower valve, which has a spoon-like shape. 

 All our individuals are much worn, but in spite of this fact the radial 

 plaits are distinct. This character, as well as the comparatively thinner 

 shell, are the only differences from the following species, of which it is no 

 doubt the representative in the Magellanian beds. I am not quite satis- 

 fied that it is really a distinct species. 



Record of specimens : Punta Arenas, Magellanian beds, upper horizon 

 (III), 21 lower, 14 upper valves (5 upper valves from the lower horizon 

 (II) of the Magellanian beds may belong to this species, but since they do 

 not show any plaits, and lower valves are absent, I am not prepared to 

 say that they really belong here). 



Distribution: Straits of Magellan (Phil.). Our specimens are appar- 

 ently from the type-locality of this species, since most of the fossils 

 described by Philippi from the Straits of Magellan (1887, p. 251) are from 

 Punta Arenas. 



Affinities: A similar species is O. bellovacina Lmck. (see Wood, 1861, 

 p. 17, pi. 3, f. i, pi. 7, f. 3) from the Lower Eocene of France and En- 

 gland, but in the latter the radial plaits are stronger, and the outline is 

 broader. 



34- OSTREA INGENS Zittel. 

 PI. XV, XVI, XVII, XVIII, and XIX, Fig. i". 



1864 O. ingens Zittel, in: Novara Exped., p. 54, pi. 13, f. 3. 



1864 O. nelsoniana Zittel, ibid., p. 55, pi. 11, f. 7. 



1,873 O. nelson. & ing. Hutton, Cat. Tert. Moll. Echin., N. Zealand, p. 34. 



1887 O. patagonica Philippi (non d'Orbigny), Tert. Quart. Verst. Chiles, 



p. 213 (pro parte, not fig. 2 on pi. 48). 

 1887 O. fermrisi Philippi (non d'Orbigny), ibid., p. 214 (not fig. 5 on 



pi. 48). 

 1887 O. botirgeoisi Philippi (non Remond), ibid., p. 215, pi. 48, f. 3. 



1896 O. beneckei Moericke, in: N. Jahrb. Min. Geol. Pal. Beil., Bd. 10, p. 

 574, pi. 13, f. i. 



1897 O.ferraresi Pilsbry (non d'Orbigny), in: Pr. Acad. Philad., p. 330. 

 1897 (Nov.) O. hatcheri Ortmann, in: Amer. Journ. Sci., v. 4, p. 355, pi. 



ii, f . i . 

 1897 O. philippii Ortmann, ibid., p. 356, pi. 11, f. 2. 



