II. PALEOZOIC TIME. 

 Subdivisions. 

 The higher subdivisions of Paleozoic time are as follows : — 



1. Eopaleozoic Section. 



I. Cambrian Era. 

 II. Lower Silurian Era. 



2. Neopaleozoic Section. 



I. Upper Silurian Era. 

 II. Devonian Era. 

 III. Carbonic Era. 



Paleozoic time is naturally divided into two sections at the break 

 between the Lower and Upper Silurian. This boundary line is marked in 

 the history by an epoch of mountain-making in eastern North America and 

 western Europe, and by a somewhat abrupt transition in the animal life of 

 the seas. These sections are here named by using prefixes to the term 

 paleozoic derived from the Greek lyws, daivn, and veos, new. 



The first of these sections, the Eopaleozoic, was characterized by the fact 

 of almost universal seas over the continental area, and of universal marine 

 life, and also by the more specific Paleozoic fact, that marine Invertebrates, 

 or the species of the inferior division of the Animal Kingdom, were dis- 

 played under nearly all their grander types before the close of this section 

 of Paleozoic time ; and also that the highest division of the Animal King- 

 dom, Vertebrates, was represented by species of the inferior type of Fishes. 



The second of the sections, the Neopaleozoic, was characterized by the 

 gradually increasing extent of dry land over the continental area, and the 

 covering of the emerged surface with land plants, and finally with great 

 forests ; and also by the multiplication of terrestrial species of animal life 

 among Invertebrates, and finally among Vertebrates. With the progress of 

 the era. Cryptogams, plants of the lower division of the Vegetable Kingdom, 

 reached their culmination in grade, size, and diversity of kinds ; and the 

 superior division of the Vegetable Kingdom, Phaenogams, was represented 

 by species of the inferior type of Gymnosperms. 



The Eopaleozoic section was, biologically, following Agassiz's method of 

 designation, the time of the Eeign of the Invertebrates, and prominently of 

 Trilobites ; the Neopaleozoic, in its Upper Silurian and Devonian eras, the 

 time of the Eeign of Fishes^ and in the Carbonic era, that of the Reign of 

 Amphibians. 



The first real progress in correlating the Paleozoic rocks of North America and 

 Europe was made through the labors of the geologists of the survey of the State of New 

 York, and those of Murchison, Sedgwick, De Verneuil, and others abroad. But, in this 



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