ORTMANN : TERTIARY INVERTEBRATES. I I I 



1887 O. remondi Philippi, ibid., p. 214, pi. 48, f. 4. 



1896 O. reni. Moericke, in: N. Jahrb. Min. Geol. Pal. Beil., Bd. 10, p. 575, 

 pi. 12, f. 2. 



1896 O. transitoria Moericke, ibid., p. 576, pi. 12, f. i. 



1897 O. patagonica Ortmann, in : Amer. Journ. Sci., v. 4, pi. 1 1, f. 4 (after 

 d'Orbigny). 



1897 O. patagonica v. Ihering, in: Rev. Mus. Paul., v. 2, p. 326 (non p. 

 222, nee pi. 9, f. 52). 



V. Ihering quotes as synonyms the following species of Philippi : O. 

 burmeisteri, O. bravardi, O. longa, O. agghitinans, O. adsociata (Anales 

 Mus. Nac. Chile, 1893): I cannot verify these, since I have no access to 

 that paper. 



Differs from O. ingens in the presence of distinct crenulations all around 

 the margin of the upper valve. 



In addition, we may mention, that there are sometimes folds on the 

 lower valve, which are irregular, and comparatively larger than these of 

 O. ingens (see the figure of O. remondi given by Philippi and our figure 

 i* on plate XX). 



Remarks: These crenulations or wrinkles are the only distinctive char- 

 acter, but it is a very good one. They are shown in one of the original 

 figures of d'Orbigny, which represents an upper valve. V. Ihering men- 

 tions them, and the two upper valves among the material sent by him to 

 the Princeton Museum show them well developed. 



Among our material, all of the 33 upper valves show these crenulations, 

 and they pass all around the margin in 26 of them. In the 7 remaining 

 the lower margin is either broken away, or so much worn, that the crenu- 

 lations have been obscured, but they are always seen at least in certain 

 parts of the margin. In the 103 upper valves of O. ingens in our collec- 

 tion in which the inner side is exposed, crenulations are never seen all 

 around the margin, and only in 13 valves from the Patagonian beds, and 

 in 14 from the Cape Fairweather beds they are present for a short dis- 

 tance near the area. 



We cannot wish any better specific character in an oyster! 



To the crenulations of the upper valve correspond, in the lower valve, 

 little grooves. But these are in most cases obliterated, or have been 

 destroyed by the mutilation of the margins. So it is difficult, in many 

 cases, to identify isolated lower valves, unless radial ribs are present. 



