80 THE MOUNTAIN. 



be expected from the analogy of the laws governing the 

 distribution of living invertebrate animals. A contrary 

 opinion has prevailed very widely, it being rashly assumed 

 that at remote epochs the majority of species were far 

 more cosmopolite than in modern times." 



He further proceeds, " The recent researches of Murchi- 

 son and De Yerneuil, point to the conclusion that the fossil 

 shells, corals, and trilobites of the Silurian system of Scan- 

 dinavia and Russia greatly resemble those of the British 

 Isles ; yet nearly half the species which they collected there 

 were different from ours, and the departure from a common 

 type was far more conspicuous in the lower Silurian fossils 

 of Britain and Russia than in those of the upper division. 



"When the same fossils of Northern Europe were com- 

 pared by De Yerneuil with those brought by me from Ame- 

 rica, the distinctness was obviously much greater, although 

 the representation of generic forms in the organic remains 

 of the upper and lower Silurian strata, was not clear and 

 satisfactory. " 



He then adduces the negative evidence which would tend 

 to the conclusion of the identity of the ancient fossiliferous 

 rocks of Europe and America, and seems to have no diffi- 

 culty in demonstrating their parallelism. 



To the Onion-Peel formula there have been some dis- 

 senters. They object to the classification now existing as 

 "not possessing scientific elements of generalization suf- 

 ficiently universal." That the out-cropping edges of 

 groups of geological formations, such as appear in the 

 British Islands, the mere rim of vast basins like the old 

 continent, that an insignificant fragment, as England is, of 

 so vast an area as the eastern hemisphere, should give a 

 classification to the geology of whole continents, and the 

 whole world, and this in a nomenclature derived from a 

 purely geographic origin, without any elements of geologi- 

 cal science at its foundation, they have objected to. 



Of course, this objection can also be made to any attempt 

 to identify by name all the rocks of this country. 



The vertical section of Pennsvlvania rocks shows the 



