Bulletin Volume 90

Bulletin Volume 90

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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. 1906 edition. Excerpt: ...specimens have not yet come under observation. The types of the species come from the Fort Cassin beds at Fort Cassin Vt. Eurystomites virginianus Hyatt Eurystomites virginiana Hyatt. Am. Phil. Soc. Proc. 1804. 32:444 Hyatt states under the description of this species, the types of which were found near Lexington Va., that "there is a young specimen in the American Museum under the name of kelloggi, from Fort Cassin, that appears to belong to this species, having similar sutures, form of whorl and involutions." E. virginianus is characterized as having "more cylindrical whorls and more numerous and straighter sutures at all stages than in k e ll o g g i." We have not observed any adult specimens referable to this species in the collections from the Champlain basin. Genus Tarphyceras Hyatt This genus has been separated from Eurystomites Schroder by Hyatt 1894, p. 433. The latter author states the relation of the two genera as follows: This genus has heretofore been confounded with Eurystomites by Schroder, the species being found together and resembling each other in general aspect. It differs, however, from that genus in having a more discoidal form, more numerous and more slowly growing whorls, in length of living chamber, in form, aperture and other characters. As to the differences in the length of the living chamber, it has been asserted later on p. 442 by Hyatt that the living chamber in Eurystomites is very variable in length, shorter than in Tarphyceras in the adult E. kelloggi, and in the aged specimens very long. The length of the living chamber can, therefore, hardly be relied upon for generic distinction. The aperture of Eurystomites has prominent lateral crests, at least in E. kelloggi, while in Tarphyceras...show more

Product details

  • Paperback
  • 189 x 246 x 3mm | 122g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236990935
  • 9781236990938