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THE ARKANSAS COAL MEASURES.
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Carboniferous age, from Shinall mountain. In quarries in the sandstones of Big Rock, near the city of Little Rock, are found plant remains of indeterminable character. The stratigraphy of the Survey places both localities in the Lower Coal Measures, and probably above the fossiliferous sandstones of Bee Rock, on Little Red river.

The Pacific Carboniferous Sea.

Revolution in Devonian time.—In Paleozoic times there have been many revolutions and alternations of continents and seas, and consequent readjustment of their inhabitants to new surroundings. One of the greatest of these was that which broke up a large zoölogical province, and put in direct connection regions that before were separated.

Dr. A. Ulrich[1] has shown that in lower and middle Devonian the faunas of Bolivia, Brazil, the Falkland Islands, and South Africa were very similar to those of North America, and that they were very different from the faunas of Europe and Asia. This state lasted until the end of the middle Devonian, when the revolution began. Professor H. S. Williams[2] has shown that with the beginning of the upper Devonian in America there came in a fauna, many species of which were not the direct descendants of those immediately preceding them. This new fauna was, however, closely related to forms known in Europe and Asia, but unlike those of the southern regions.

Professor Williams[3] afterwards elaborated this theory, and followed out closely the changes that were inaugurated towards the end of the Devonian. The culmination of these changes produced the Pacific Carboniferous sea.

The Carboniferous sea.—From chapter V., in Suess' "Antlitz der Erde," Vol. II., we get many valuable suggestions as to the outlines of the Pacific Carboniferous ocean. The Subcarbonifer-

  1. ↑ Beiträge zur Geologie und Paläontologie von Südamerika, I., "Paläozoische Versteinerungen aus Bolivien."
  2. ↑ Bull. Geol. Soc. America, Vol. I., "The Cuboides Zone and Its Fauna.
  3. ↑ Proc. Amer. Assoc. Adv. Sc., 1892, Section E, Address, "The Scope of Paleontology and Its Value to Geologists."
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