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. patagonic a 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. bourgeoisi Remond, 
which was a mistake, as O. bourgeoisi 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). 
Moericke, 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. ingeus. 
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. 
