406 Geological Memoirs. 



" The first result is, that the peculiar infusorial mass is not con- 

 find to the one stratum first made known, although the others re- 

 cently laid bare do not equal that in purity and regularity. 



" From the relations of the originally exposed infusorial stratum, 

 the immediate deposit of the whole series of volcanic tuifs and conglo- 

 merates containing that bed, and resting upon the grauwacke, is dis- 

 tinctly seen. 



" The thickness of the conglomerate and tuff, as far as it has been 

 hitherto proved, amounts to about 27^ fathoms or 1 65 feet ; and 

 it is not likely that the whole thickness is much greater than this, 

 since the grauwacke comes out to this day at no great distance 

 towards the north-east. 



" Notwithstanding that the whole thickness of the deposit has not 

 been penetrated at this point, there is no doubt that the series of 

 deposits upon the grauwacke consists exclusively of various conglo- 

 merates and tuffs of volcanic origin, having very different thickness, 

 and containing, interstratified with them, several infusorial masses ; 

 and the whole sequence is essentially identical with the very similar 

 series in the neighbourhood of the Laacher-See." 



The microscopic investigation of the thirty-nine specimens for- 

 warded has led to the following results : — 



1 . The whole stratified deposit of volcanic tuff and conglomerate 

 reposing on the grauwacke at Hochsimmer, just as in the case of 

 the Brohl Valley, and the similar masses on the east bank of the 

 Rhine (e. g. the pumiceous conglomerate or sandstone of Engers), 

 all exhibit relations with minute organic life, and are often, to all 

 intents and purposes, actually formed of microscopic animalcules. 



The relation with organic beings is of this kind : not only are 

 there complete layers of distinctly recognisable organic bodies, which 

 were once the siliceous cases of infusorial animalcules, but, with few 

 exceptions, every fragment of tuff not larger than a pin's head will 

 be found to contain several portions, sufficiently preserved to enable 

 us to identify specific forms, and often exhibit complete shells of 

 these minute beings ; sometimes also the whole mass is almost 

 entirely made up of them. 



In the rock at Brohl and the firestone of Bell, it is the included 

 pumice which exhibits remains of this kind either complete or in a 



