EAELY PALEOZOIC BKYOZOA OF THE BALTIC PROVINCES. 



43 



Ordovician faunas in Russia and Arctic America, of Arctic origin and 

 development, tlie upper Lyckholm-Borkholm fauna is more sharply 

 distinguished from the lower Lyckholm and preceding faunas than the 



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Fig. 3.— Generalized paleogeogeaphic map showing supposed distribution of land and -water 

 DURING Black Rivee (decorah) and early Trenton (prosser) times. Actual outcrops shown 

 IN black. 



latter are from each other. This fact offers another argument for 

 the behef that a line passes through the Lyckholm that represents a 

 very considerable time break and adds to the plausibihty of the cor- 

 relation of the Wesenberg as not younger than early Trenton. 

 92G02°— Bull. 77—11 5 



