Elements of geology - a text-book for colleges and for the general reader (1892) (21069255568)

Title: Elements of geology : a text-book for colleges and for the general reader
Identifier: elementsofgeolog00leco (find matches)
Year: 1892 (1890s)
Authors: LeConte, Joseph, 1823-1901
Subjects: Geology
Publisher: New York : D. Appleton and Co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library



Text Appearing Before Image:
JURASSIC ANIMALS. 437 boidal enameled scales, pavement palatal teeth, and persistent note- chord (Fig. 682). Reptiles.—The huge reptiles which form the distinguishing feat- ure of this age culminate in the Jurassic period. Their number and variety are so great that we can only select a few from each order for
Text Appearing After Image:
Fig. 685. Fig. 686. Figs. 683-686.—Jurassic Reptiles—Ichthyosaurus and Plesiosanrus: 683.—Ichthyosaurus commu- nis, x y^j. 684. Plesiosaurus dolichodeirus, restored, x ^j. 685. Vertebras of Ichthyosaurus and Section of same, showing structure. 686. Tooth of Ichthyosaurus, natural size. description. They were emphatically rulers in every department of Nature—rulers of the sea, of the land, and of the air. We shall treat of them under the three heads thus indicated, viz.: 1. Enaliosaurs (sea-saurians), or rulers of the sea; 2. Dinosaurs (huge saurians), or rulers of the land; and, 3. Pterosaurs (winged saurians), or rulers of the air. The first were wholly swimming, the second walking, the third flying, saurians. Intermediate between the first and second was a fourth order, the Crocodilians, which both swam and crawled. 1. Enaliosaurs.—From the immense variety of these we select only two for description as representative genera, viz., Ichthyosaurus and Plesiosaurus (Figs. 683 and 684). The Ichthyosaurus (fish-lizard) was a huge animal, in some cases thirty to forty feet in length, with a stout body, short neck, and enor- mous head, sometimes five feet long, and jaws set with large conical, striated teeth, sometimes 200 in number. The enormous eyes, some- times fifteen inches in diameter, were provided with radiating, bony plates (sclerotic bones), as are the eyes of birds and some living and