CONTEMPOEAEIES AND SUCCESSORS OF EOZOON. 145 



" This fact being establisliedj I procured from tlie 

 quarries near Passau as many specimens of tlie lime- 

 stone as the advanced season of the year would per- 

 mit j andj aided by my diligent and skilful assistants^ 

 Messrs. Reber and Schwager^ examined them by the 

 methods indicated by Messrs. Dawson and Carpenter. 

 In this wa,y I soon convinced myself of the general 

 similarity of our organic remains with those of Canada. 

 Our examinations were made on polished sections and 

 in portions etched with dilute nitric acid, or, better, 

 with warm acetic acid. The most beautiful results 

 were however obtained by etching moderately thin 

 sections, so that the specimens may be examined at 

 will either by reflected or transmitted light. 



^^ The specimens in which I first detected Eozoon 

 came from a quarry at Steinhag, near Obernzell, on 

 the Danube, not far from Passau. The crystalline 

 limestone here forms a mass from fifty to seventy 

 feet thick, divided into several beds, included in the 

 gneiss, whose general strike in this region is N.W., 

 with a dip of 40°-60° N.E. The limestone strata of 

 Steinhag have a dip of 45° N.E. The gneiss of this 

 vicinity is chiefly grey, and very silicious, containing 

 dichroite, and of the variety known as dichroite- 

 gneiss ; and I conceive it to belong, like the gneiss of 

 Bodenmais and Arber, to that younger division of the 

 primitive gneiss system which I have designated as 

 the Hercynian gneiss formation; which, both to the 

 north, between Tischenreuth and Mahring, and to the 

 south on the north-west of the mountains of Ossa, 



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