THE MOUNTAIN. 79 



rocks all bearing some particular name, generally of the 

 locality where they are most largely developed. For ex- 

 ample, Mohawk and Trenton limestone, Salmon River lime- 

 stone and shales, Rochester shales, etc. etc. ; or they are 

 again named from some striking character, as Pentamerus 

 limestone, Gypseous shales, Gray Brachiopodous sandstone, 

 Olive sandstone, etc. etc. 



These are again classified according to European nomen- 

 clature, as different members of the Transition series, Cam- 

 brian, or Silurian, etc. etc. Speaking of this classification, 

 Mr. Lyell says, " Their grouping of the subordinate mem- 

 bers of the Devonian and Silurian systems, has been based 

 on sound principles, on mixed geographical, lithological, 

 and paleontological considerations ; and the analogy of Eu- 

 ropean Geology teaches us that minor subdivisions how- 

 ever useful and important within certain limits are never 

 applicable to countries extremely remote from each other, 

 or to areas of indefinite extent. The thinning out and dis- 

 appearance of the mud-stones and sandstones of the more 

 Eastern States, causing limestones, such as the Helderberg 

 and Niagara, so widely separated in New York, to unite and 

 form single and indivisible masses in Ohio, affords no argu- 

 ment against the classification of the New York geologists. " 



He then proceeds to enumerate the species of fossils 

 which he had inspected that were common to the rocks of 

 Ohio, Sweden, and Russia. 



These are a number of Trilobites, as the Isotelus gigas, 

 Paradoxides, Trinucleus, Asaphus, etc. etc. Also of shells, 

 as the Spirifer lynx, regarded by Murchison and De Yer- 

 neuil as very characteristic of the Silurian beds of Sweden 

 and Russia ; also others of the same order, Leptoena seri- 

 cea, Orthis-striatula, Pterinea, Cypricardia, Orthoceras, and 

 Bellerophon bilobatus. He also enumerates the Crinoideas 

 or Stone Lilies, and then proceeds, " In regard to the pro- 

 portion of the species common to the Silurian beds of Eu- 

 rope and America, whether of the lower or upper divisions, 

 I may confidently affirm that it is not greater, than would 



