. Elements of geology : a text-book for colleges and for the general reader. Geology. 400 PALAEOZOIC SYSTEM OF ROCKS. as we approach the time for the appearance of Reptiles, some of these Sauroid fishes seem to become still more reptilian in character, while others become more fish-like. Reptiles—Amphibians.—The first known appearance of the class of Reptiles on the earth was in this age : not yet, however, in as great numbers or size, or as high in the scale of organization, as in the next age. The reign of Reptiles had not yet commenced. The class of Reptiles may be divided into two sub-clas
. Elements of geology : a text-book for colleges and for the general reader. Geology. 400 PALAEOZOIC SYSTEM OF ROCKS. as we approach the time for the appearance of Reptiles, some of these Sauroid fishes seem to become still more reptilian in character, while others become more fish-like. Reptiles—Amphibians.—The first known appearance of the class of Reptiles on the earth was in this age : not yet, however, in as great numbers or size, or as high in the scale of organization, as in the next age. The reign of Reptiles had not yet commenced. The class of Reptiles may be divided into two sub-classes, viz., True Reptiles and Amphibians. The Amphibians differ so greatly from other Reptiles that they are now usually made a distinct class, inter- mediate between Fishes and True Reptiles. Of these two sub-classes only the Amphibians are certainly known to have been represented in the Carboniferous. Again, Amphibians are subdivided into four or- ders, viz.: 1. Tailless Amphibians (Anoura), such as frogs, toads, etc.; 2. Tailed Amphibians (Urodela), such as tritons, salamanders, sirens, etc.; 3. The rare snake-like forms (Ophiomorpha or Gymnophiona); and 4. Labyrinthodonts. Of these, only the Labyrinthodonts were repre- sented in the Carboniferous. The other three orders still exist, but the last has been long extinct. The Labyrinthodonts were very large, often gigantic reptiles. They were most of them salamandriform, with long tail, weak limbs, and sluggish movement. Some were pisciform, and had paddles instead of feet. We can only briefly describe a few representatives of the class, and draw some conclusions. 1. Reptilian Footprints.—In the sub-Carboniferous of Pennsylvania, near Pottsville, have been found tracks of a four-footed, crawling ani- mal (Sauropus primcevus), having thick, fleshy feet about four inches long, and making a stride of about thirteen inches. The impression of. Fig. 577.—Fossil Bain-prints of the Coal Period. a dragging tail is also visible. T
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1892
