. The doctrine of descent and Darwinism. Evolution. V- THE DOCTRINE OF DESCENT. terms them Placoids, from the rhombic scales, provided witli a layer of enamel highly favourable to preserva- tion, and covering the whole surface in oblique Fig. II. The vertebral column, as in the sharks, enters the upper flap of the tail and renders it strikingly unsymmetrical. The Ganoids are, as comparative anatomy has proved with certainty, a development of the shark-like fishes, if not decidedly of a higher grade. The Ganoids, there- fore, presuppose the shark. The carboniferous period owes its name t
. The doctrine of descent and Darwinism. Evolution. V- THE DOCTRINE OF DESCENT. terms them Placoids, from the rhombic scales, provided witli a layer of enamel highly favourable to preserva- tion, and covering the whole surface in oblique Fig. II. The vertebral column, as in the sharks, enters the upper flap of the tail and renders it strikingly unsymmetrical. The Ganoids are, as comparative anatomy has proved with certainty, a development of the shark-like fishes, if not decidedly of a higher grade. The Ganoids, there- fore, presuppose the shark. The carboniferous period owes its name to the enor- mous accumulation occurring in its midst, of the remains of terrestrial plants, fern-like Calamites, and more especially of Sigillaria and Lepidodendra, stand- ing between vascular Cryptogams and Conifers. They formed tropical bog-forests, such as Franz Unger some years ago attempted to restore in an ingenious compo- sition. In these steaming primaeval forests, differing from the early beginnings of antecedent periods by their extent and luxuriance, new phases of animal life become manifest—scorpions, myriapods, and in- sects—in other words, air-breathing Articulata, and likewise the first air-breathing V^ertebrata. The latter,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Schmidt, Dr. (Eduard Oskar), 1823-1886. New York, D. Appleton
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