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first rocky crust into several parts. Tliese may be generally known as 

 the Azoic Paleozoic, Mesozoic and Cenozoic. By the first, the 

 Azoic, is known that portion as yet held to be devoid of organic 

 remains. This has, however, by some been subdivided into two, 

 the Azoic and Eozoic, from the discovery of certain structures 

 which have been regarded by some authorities as of organic origin 

 in certain portions of these earliest rocks, more especially of tliat 

 peculiar so-called organism known as the Dawn Animal, or Eozoon 

 Ganadensp., which has the honor of being regarded as our first known 

 form of life. It is but fair, however, to state that the organic nature- 

 of this substance has been strongly combated by many scientific men, 

 the great defender of its organic nature at present being Sir William 

 Dawson, through whose efforts and researches it was first most promi- 

 nently brought into notice, and who has devoted more time and close 

 study to its history than pi-obably any other person. Some, Jiowevei-, 

 liold that in this Azoic time, or the Eozoic part of it, evidences of 

 organic life are manifest in the presence of the beds of graphite or carbon, 

 which are claimed to represent the early presence of vegetable matter 

 in some form. The beds of ii-on ore are also regarded by some as 

 indicating the presence of organic agencies as well as our deposits of 

 Apatite. These, however, are all as yet subjects of controversy and 

 will probably remain so for many years. The Azoic may be said to 

 embrace two periods, the Laure7itian and Iluronian, and is followed 

 by the Paleozoic, a time when organic life flourished everywhere over 

 the world's surface, and so generally were the species distributed that 

 precisely the same forms are found at points the most widely removed. 

 The Primary or Paleozoic time embraces several periods, or systems 

 so-called, including the Cambrian of our nomenclature, or tlie Lower 

 Silurian of earlier times, the Cambro-silurian or middle Silurian, the upper 

 Silurian or Silurian proper, the Devonian, Carboniferous and Permian ; 

 and forms the longest and probably the most important portion, in many 

 ways, of the earth's history. The succeeding time, the second-iry or. 

 Mesozoic, embraces the Triassic, Jurassic and the Cretaceous, wiiile the 

 Tertiary or Cenozoic includes the Eocene, Miocene and Pliocene. The 

 closing period, the Post-tertiary, includes the Pleistocene, recant and 

 prehistoric. 



