( 422 ) 
Geology. — “On Jurassic fossils as rounded pebbles in JSortli- 
Brabant and Limburg ”. By Dr. P. Tesch (communicated by 
Prof. G. A. F. Molengraaff). 
(Communicated in the meeting of October 30, 1909). 
It is now a year ago that I drew the attention to the fact that 
the so-called “Kieseloolithstufe” of the Lower Rhine basin, recognised 
as a separate formation in 1905 by German geologists, proves 
to be also represented in the territory of Northern-Liinburg '). At 
that time especially the stratigraphical conditions of these flu viable 
strata were discussed, this factor having proved to be of practical 
interest for the explorations of coal in these regions and the remark¬ 
able silicified fauna being found in these deposits was only mentioned 
in passing. After having finished this paper the collected material of 
fossils originating from the sands of this geological horizon has still 
greatly increased. This augmentation is owing, besides to the new 
borings executed since that time, to the discovery of a good finding- 
place in a clay-pit in the hills east of Reuver during this summer '), 
so that the collection now at my disposal is complete enough to 
enable us to draw some conclusions concerning the geological age 
of this silicified fauna and to compare these results with the opinions 
published by other authors about this subject. 
So for the discussion of the stratigraphical and lithological cbtnpo- 
sition of these strata referring to my former papers treating this 
subject and to the literature which is mentioned there, I have to 
study in the first place the results obtained by others when examining 
those fossils of neighbouring German places. 
These silicified and rounded petrifactions are mentioned for the 
first time by Prof. Dr. J. Pohlig at Bonn in the “Verhandlungen 
des naturhistorischen Yereins der preuss. Rheinlande und Westfalen , 
1883, second half, page 225. Here the following genera are enumerated, 
originating from the white coarse sands of Duisdorf, not far from Bonn . 
Milioliden ? Cardium 
Vioa Mytilus 
Astraea ? Pholas 
Encrinus Purpura 
h P- Tesch. Der niederlandische Boden und die Ablagerungen des Rheines uml 
der Maas aus der jiingeren Tertiar- und der alteren Diluvialzeit. Amsterdam, 190»- 
2 ) P. Tesch. De klei van Tegelen, een onderdeel der “Kieseloolithstufe”. Tijd- 
schrift van bet Kon. Ned. Aardrijksk. Gen. Dee! XXV! (1909), p. 573 
