Memoir Volume 6

Memoir Volume 6

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1904 edition. Excerpt: pass. Yet the general expression of the Devonic shells here embraced under this name is distinctive, and, so far as external evidence goes, they may with safety be referred to Paracardium. They are shells of circular marginal outline, high and slightly projecting beaks and fine simple radial ribs without other ornament. With regard to hinge structure Con. rath1 has indicated that the hinge line bears denticulations which have no 'Sitzb. der kais. Akad. der Wissensch. 1 Abth. 1887. p. 9. relation to the sculpture ribs, but this observation was made on Siluric shells, and we have been able to find no corresponding structure in the delicate barite replacements derived from the Naples beds. These shells are of diminutive size, and such cardinal features as they possess are very obscure. Paracardium doris Hall Plate n, fig. 5-10 Cardiola doris Hall, Paleontology of New York. 1883. v. 5, pt 1, plates and explanations, pi. 70, fig. 10, 11 Paracardium doris Hall, Paleontology of New York. 1885. v. 5, pt 1, p. 428, pi. 70, fig. 10, 11 Shell very small, subcircular in outline when uncompressed, but usually somewhat elongate transversely or obliquely. Beaks minute, incurved and directed forward, umbones full and convex, the general contour of the shell being rotund and regular. Hinge line quite short and but slightly interrupting the regularity of the periphery. Surface covered with 20 to 25 fine rounded ribs, separated by narrower furrows. Occasionally these ribs show very faint traces of concentric lines. The shell rarely has a length and breadth exceeding 4 mm. Habitat. Genesee province; Naples subprovince. Common in the Styliola limestone in Ontario county and in the lower, soft shales of the Naples beds in Yates, Ontario, Livingston and more

Product details

  • Paperback | 80 pages
  • 189 x 246 x 4mm | 159g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 123662419X
  • 9781236624192