. The chain of life in geological time [microform] : a sketch of the origin and succession of animals and plants. Paleontology; Paleobotany; Paléontologie; Paléobotanique. 132 THE CHAIN OF LIFE. of land-plants in che Devonian and Carboniferous. Another curious illustration of the diminishing necessity for air-breathing to the fishes, is the change of the tail from the unequally-lobed or heterocercal form, which pre- vailed in the Palaeozoic, to the more modern equally-lobed (homocercal) style in the Meso- zoic. The former is better suited to animals which have to rise rapidly to the surface fo
. The chain of life in geological time [microform] : a sketch of the origin and succession of animals and plants. Paleontology; Paleobotany; Paléontologie; Paléobotanique. 132 THE CHAIN OF LIFE. of land-plants in che Devonian and Carboniferous. Another curious illustration of the diminishing necessity for air-breathing to the fishes, is the change of the tail from the unequally-lobed or heterocercal form, which pre- vailed in the Palaeozoic, to the more modern equally-lobed (homocercal) style in the Meso- zoic. The former is better suited to animals which have to rise rapidly to the surface for air, and is still continued in some modern fishes, which for other reasons need to ascend and descend, or to turn them- selves in the water; but the homocercal form is best suited to the ordinary fish, whether Ganoids or Teleosts (Fig. 122). It is curious also to find the beginning of the dominancy of the ordinary fish to coincide with. Fig. 119. -Tooth of a Tertiary Shark (Carcfiarodon).. 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 Dawson, J. W. (John William), Sir, 1820-1899. London : Religious Tract Society
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectpaleontology, bookyea
