Reports Dealing with the Systematic Geology and Paleontology of Maryland Volume 4

Reports Dealing with the Systematic Geology and Paleontology of Maryland Volume 4

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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. 1911 edition. Excerpt: ... cm. Maximum width 1.2 cm. to 5 cm. Texture coriaceous. Midrib rather stout and' prominent. Lateral veins thin but distinct, especially on the lower surface, more or less closely placed, parallel, curving backward from the midrib, and then straight or slightly curved upward to the margin. Angle of divergence wide, 45 to 90. Veins either simple or forked, the forking usually near the base, both kinds often shown on a single specimen. This species is based entirely upon very fragmentary material, which served Fontaine for the differentiation of five species of Angiopteridium and two species of Anomozamites. There is absolutely no ground for the reference of any of the material to the genus Anomozamites, and it is all obviously identical. There is some slight variation from specimen to specimen, for example the midrib is somewhat less stout in Angiopteri diam nervosum and densineroe, as delimited by Fontaine, and the angle of divergence is somewhat more acute in the latter, but these are not characters of specific value. If similar recent fronds, such as those of Oleandra, 1-lngiopteris, or Marattia be examined, the size of the midrib, the remoteness or closeness of the lateral veins and their angle of divergence will be found to vary through much wider limits, a single frond often exhibiting the extremes in this respect. A single specimen from Fredericksburg figured by Fontaine (1890, pl. xxix, fig. 9), and showing apparently the basal portion of three pinnae lying in the same plane and direction, and two of them attached to stout bits of rachis, is the only evidence that the fronds were pinnate and not simple. These may represent aerial stalks, or they may equally well be interpreted as fragments of a rhizome or a rootstock. This...show more

Product details

  • Paperback | 194 pages
  • 189 x 246 x 10mm | 354g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236943848
  • 9781236943842