136 HISTORICAL PALAEONTOLOGY. 



Canada represent the shallow-water shore-deposits of the same 

 period. In fact, the former of these last-mentioned de- 

 posits contains no fossils which can be asserted positively 

 to be marine (unless the Eurypterids be considered so) ; and 

 it is even conceivable that it represents the sediments of an 

 inland sea. Accepting this explanation in the meanwhile, 

 we may very briefly consider the general succession of the 

 deposits of this period in Scotland, in Devonshire, and in 

 North America. 



In Scotland the " Old Red " forms a great series of arena- 

 ceous and conglomeratic strata, attaining a thickness of many 

 thousands of feet, and divisible into three groups. Of these, 

 the Loiver Old Red Sandstone repose with perfect conform- 

 ity upon the highest beds of the Upper Silurian, the two for- 

 mations being almost inseparably united by an intermediate 

 series of " passage-beds. " In mineral nature this group con- 

 sists principally of massive conglomerates, sandstones, shales, 

 and concretionary limestones; and its fossils consist chiefly of 

 large crustaceans belonging to the family of the Eurypterids, 

 fishes, and plants. The Middle Old Red Sandstone consists of 

 flagstones, bituminous shales, and conglomerates, sometimes 

 with irregular calcareous bands; and its fossils are principally 

 fishes and plants. It may be wholly wanting, when the Upper 

 Old Red seems to repose unconformably upon the lower divi- 

 sion of the series. The Upper Old Red Sandstone consists of 

 conglomerates and grits, along with a great series of red and 

 yellow sandstones the fossils, as before, being fishes and re- 

 mains of plants. The Upper Old Red graduates upwards 

 conformably into the Carboniferous series. 



The Devonian rocks of Devonshire are likewise divisible 

 into a lower, middle, and upper division. The Lower 

 Devonian or Lynton Group consists of red and purple sand- 

 stones, with marine fossils, corresponding to the " Spirifer 

 Sandstein " of Germany, and to the arenaceous deposits (Scho- 

 harie and Cauda-Galli Grits) at the base of the American 

 Devonian. The Middle Devonian or Ilfracombe Group consists 

 of sandstones and flags, with calcareous slates and crystalline 

 limestones, containing many corals. It corresponds with the 

 great " Eif el Limestone " of the Continent, and, in a general 

 way, with the Corniferous Limestone and Hamilton Group of 

 North America. The Upper Devonian or Pilton Group, lastly, 

 consists of sandstones and calcareous shales which correspond 

 with the " Clymenia Limestone " and Cyprindina Shales " of 



