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Turritella 
Turbo 
Dentalium 
Pentocrinus 
Cidaiis 
Serpula 
Terebella 
Membranipora 
Monticulipora 
Ostrea 
Spondylus 
Pecten. 
The author believes those genera to prove an upper-senonian age 
for these organisms. The next year H. vox Dechen already suggested 
some doubt as to the correctness of this conclusion in “Brlau ter ungen 
zur geologischen Karte der Rheinprovinz und der Provinz Westfalen”, 
second volume, 1884, page 626. Meanwhile it was only in 1897 
that the incorrectness of this opinion was demonstrated convincingly. 
In this year C. Schluter published in his paper: “Zur Heimatfrage 
jnrassiseher Geschiebe im Westgermanischen Tieflande” (Zeitschr. 
der deutschen geol. Gesellsch., Volume 49, 1897, page 486) the 
results of his examination of the petrifactions of Duisdorf, in conse¬ 
quence of which he expresses this opinion that this fauna originates 
from upper-jurassic strata. By this author the following fossils are 
mentioned, all collected in the same gravel-pits of Duisdorf near 
Bonn-. 
Tkamnastraea ( Astraea ) microconus Goldf. ? 
Millericrinus horridus d’Orb. (M. echinatus Schloth. sp .) (many 
stems in different varieties). 
Cidaris florigemma Phill. (spines). 
Gidans psammosa Mosch. ? (fragment of spines). 
Rhabdocidaris trispinata Quenst. ? (fragment of spines). 
Serpida (tubes). 
Rhynchonella ? (fragment). 
Ostrea gregaria Soiv. ? (fragment). 
Ostrea hastellata Schloth. f (fragment). 
Ostrea pulligera-ascendens Quenst. ? (fragment). 
Exogyra reniformis Goldf. ? (fragment). 
Pecten vitreus Pom. ? (printing). 
Turritella jurassica Quenst. ? 
t ' Schluter believes that those fossils more specially must belong 
the middle part of the Oxford- horizon and must originate 
r°m the “Terrain a chailles” (“Seguanien inferieur”) of French 
oimine, southern Baden, upper-Alsace, northern Switzerland and 
the Jura-mountains, 
