Bulletin of the American Museum of Natural History Volume 20

Bulletin of the American Museum of Natural History Volume 20

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1904 edition. Excerpt: ...by the condition of the molar teeth, which are nearly worn away to the fangs," 2 and in consequence all the enamel inflections were converted into isolated lakes before their disappearance, as in other Castoridae. Eucastor certainly had four teeth in each jaw, as indicated by Leidy 3 and shown by all our specimens. It appears, therefore, that there are no generic characters to separate it from Dipoides, to which Schlosser has already remarked its resemblance in pattern..' Dipoides tortus (Leidy). Three lower jaws agree in size with this species. One is almost complete, and affords some interesting comparisons with Stencofiber and Castor. The jaw is longer anteriorly than in these genera, the incisor more horizontal in direction, considerably less robust, with convex anterior face (nearly flat in Stencofiber and Castor) and the tip drawn to a much more slender chisel-edge than in the true beavers. The descending process at the posterior end of the symphysis is quite small, and the jaw is not so deep at this point nor the symphysial angle so abrupt. The internal inflection of the angular border of the jaw is very marked, especially at its anterior end just behind the grinding series, and the pterygoid fossa is very deeply excavated; but the angle is not produced backwards like that of Castor, so that the outline of this part is decidedly peculiar. Unfortunately the posterior border of the angle is incomplete, so that we cannot decide whether it was produced as in Haplo 1 "As the number of molars is one of the important characters of the Kenus. it should perhaps be stated that, although the head bones extend backward beyond the molars, no sign of a fourth tooth could be found on either side."--Bull. Dept. Geol. Univ. Cal.....show more

Product details

  • Paperback
  • 189 x 246 x 9mm | 304g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236911628
  • 9781236911629