150 Geological Society: — 



ai'e practically unfossiliferous, while in the other series there is evi- 

 dence of marine life and the remains of a fauna ranging upwards 

 into the Lias. Hence the author proposed to class these Lower 

 Bhaerics with the Trias, and regard the Bhoetic series as commencing 

 with the hase of the Aviada-eontorta group. 



5. " On the Silurian and Cambrian Strata of the Baltic Provinces 

 of Bussia, as compared with those of Scandinavia and the British 

 Islands.*' By Dr. F. Schmidt. Communicated by Dr. H. "Woodward, 

 F.E.S., F.G.S. 



The Cambrian and Silurian strata in question are found stretching 

 over an area 400 miles long by 80 miles wide. The country occu- 

 pied by these strata is a nearly uniform plain covered by glacial 

 deposits ; but sections are presented by the sea-cliffs, which are from 

 90 to 150 feet high. The strata consist mainly of marls and lime- 

 stones, arenaceous deposits being rare ; and they form a continuous 

 series from the base of the Cambrian to the top of the Silurian, the 

 whole of these strata being in conformable succession and unconform- 

 ably overlain by the Devonian. Although the representative of the 

 Cambrian or Primordial Silurian contains neither Paradoxides nor 

 Olenus. nor, indeed, any Trilobites whatever, but only Lingulidse and 

 Graptolites, yet its stratigraphieal position leaves no doubt as to its 

 age. The Lower Silurian or Ordovician is the richest of the divi- 

 sions, the strata of this age forming a perfectly continuous series. 

 The author divides these beds into the stages B, C, D, E, and F, 

 several of which are divisible into substages. Of the Stage B the 

 lowest bed, 1 to 10 feet thick, consists of the Glauconite-bands con- 

 taining the casts of Foraminifera described by Ehrenberg, which 

 correspond to the Oeratopyge stage of the Scandinavian geologists. 

 Above this, and closely connected with it, is the Glauconite-limestone, 

 from 12 to 40 feet thick. Next comes the famous 0rt7nVlimestone, 

 a thin bed with a very interesting fauna, corresponding to that of 

 the PhyUor/,Yq)t»s-schists. The author's beds C, D, E, and F can be 

 paralleled with the strata of Scandinavia, but have no exact repre- 

 sentatives in the British Islands. The stage E appears to represent 

 the Bala of England or the Trenton of North America. Although 

 there is no stratigraphieal break, there is a marked palaeontological 

 division between the Epper and Lower Silurian, there being no 

 strata of intermediate age represented. The Epper Silurian is 

 divided by the author into the stages G, H, I, K, which can be 

 exactly correlated with the strata of Scandinavia. The stages G, H 

 do not appear to have precise representatives in the British Islands ; 

 but I is undoubtedly equivalent to the Wenlock, and E to the Ludlow. 

 In the Baltic provinces there are no representatives of the passage- 

 beds and Lower Devonian, but the Silurian strata are unconformably 

 covered by the Old Bed Sandstone with Coccosteus, AsteroUpu 

 Bothriolepis. Homogteus, and Heterostevs. there being a marked over- 

 lap between the two series. The author argues in favour of con- 

 sidering the Cambrian, Ordovician, and Silurian as forming, in the 

 Baltic provinces, one " system."' The author is able to construct a 



