ORTMANN : TERTIARY INVERTEBRATES. IOI 



sary to support the position taken by the writer by a detailed account of 

 the history of this form, and the results furnished by the examination of 

 our material. 



It is exceedingly difficult to clear up the synonymy of the large oysters 

 of Patagonia. 



The oyster described by d'Orbigny as O. patagonica has been frequently 

 and almost generally confused with the present species, but as will be 

 demonstrated below the original O. patagonica is not found at all in the 

 Patagonian formation, that is to say, below the Santa-Cruz beds contain- 

 ing mammalian remains. 



It is to be borne in mind, that O. patagonica is not recorded by d'Or- 

 bigny himself from any locality south of San Julian ; and since our col- 

 lections show, that the true O. patagonica is really present at San Julian, 

 but in a higher horizon, it is very probable, that d'Orbigny did not pos- 

 sess the species from the true Patagonian formation at all. 



The latter was first mentioned by Darwin (1846, p. 1 1 1 and passim), 

 but without being distinguished from O. patagonica. 



Philippi (1887) possessed typical specimens of the Patagonian oyster 

 from Punta Arenas, and called them by the name of O. botirgeoisi Remond, 

 which was a mistake, as O. boiirgeoisi is from the Californian Miocene. At 

 the same time he confounds, the true O. patagonica with the species found 

 at Santa Cruz, and introduces two more species: O. ferrarisi d'Orb. and 

 remondi from the Pliocene Coquimbo-beds of Chili. What he calls O. 

 ferrarisi is not the O. ferrarisi of d'Orbigny (= patagonica}, since he dis- 

 tinctly states, that crenulations of the margins are not present in his speci- 

 mens. These crenulations are the only character by which O. patagonica 

 can be distinguished from O. ingens in every case, and accordingly, 

 Philippi's O. ferrarisi must belong to O. ingens. O. remondi, on the 

 other hand, seems to belong to the true O. patagonica (see below). 



Mcericke, in 1896, mentions from the Pliocene Coquimbo-beds: O. 

 remondi and transitoria Hup., both apparently the same species as 

 Philippi's of the same names, and adds a new species : O. beneckei. The 

 latter is nothing but a very old and large, typical individual of O. iiigen*. 

 Its chief characters, the extreme thickness of the shell, the incurved beak, 

 and the elongated and large area are exhibited in many of our larger in- 

 dividuals. Incidentally Moericke (p. 575) mentions O. patagonica from 

 Santa Cruz, and it seems, he understands by this name the more circular 

 form found at this locality. 



