( 146 ) 
Finally are found in this erratic-bloek a few small valves of horn- 
shelled Brachiopoda, among which is one of Lingula or Lingulella. 
6. Besides the piece treated of just now I found a piece of sand- 
stone with Paradoxides-remains, which shows no effervescence when 
hydrochloric acid is applied to it, and which consequently is gravel-stone. 
It is a flat piece, consisting of two parts of a different nature. One 
of them is formed by sandstone and does not present many layers. 
This sandstone greatly resembles the material of which consists the 
erratic-block treated of under «, but is a little bluish. Some small 
mica-scales and glauconite-grains are also present here. The other part 
shows many more layers and has a dark bluish-grey colour. Some- 
times the layers are as thin as paper, so that the material becomes 
slate-like. 
Just as in the other piece of stone, the Paradoxides-remains are 
cream-coloured here. They are, however, too fragmentary to enable 
us to draw the conclusion that they originate from Paradoxides Tessini. 
As up to this time, however, only sandstone with this kind of Para- 
doxides has been found in diluvial grounds, and the petrographical 
nature of one part of them bears a great resemblance to that of the 
previous piece, I think I may suppose this much, and I venture to 
range this erratic-block under this head. 
I think that both pieces originate from a layer-complex of gravel- 
stone with Paradoxides Tessini-remains, which complex consisted both 
of slate-like blue-grey parts and of thicker light-coloured layers. The 
last-mentioned erratic-block may originate from the former, whereas 
the one treated of under « would be a piece of a thicker layer. 
If my supposition is not false, it may be easily explained from the 
difference in firmness and the difference in fitness for being trans- 
ported issuing from this, why in literature nothing is found about 
erratie-bloeks that should bear resemblance to the last-mentioned 
piece, whilst two or three Communications have been received about 
the finding of erratic-blocks that most probably are more like the 
piece treated of in the first place. 
The first communication we got from Rorer.') It deals with a 
piece of gravel-stone that was found in a sand-pit of Nieder-Kunzendorf 
near Freiberg in Silesia. It seems to have been more exposed to 
the influence of the weather than the erratie-bloek found by me, the 
writer mentioned speaking of a ferrugious outer crust, while round 
my piece such a crust begins to form itself. 
Probably I must also range among this kind a piece of sandstone 
1) Roemer, Zeitschr. der deutsch. geol. Gesellschaft. Bd 9. Jahrg. 1857 pag. 511, 
