SILURIAN FAUNA INTERPRETED EPICONTINENTALLY 699 
the Baltic (XXV) is constituted entirely of Silurian rocks, and 
one of the most prolific Silurian faunas known to exist in so 
small an area has been described from here. 
ei Stilurtan Areas. 
— — — Approximate 
Shore Lines. 
a a a 
Fic. 2. Outline map of the North Polar regions with the Silurian outcrops and 
the hypothetical Silurian shore lines indicated. 
The distributional evidence of the Silurian strata favorable 
to the existence of a north polar connection between the Silurian 
seas of Europe and those of the interior of North America hay- 
ing been pointed out, let us turn to the evidence of such a con- 
nection which may be afforded by the life of the period. A 
study of the Silurian faunas in the Mississippi valley, shows 
some remarkable points of resemblance with the faunas of north- 
