. Bulletin - United States National Museum. Science. 280 BULLETIN" 11, UNITED STATES NATIONAL MUSEUM. from American are shown in figure 168 for comparison with the Russian specimens referred to the variety. The thin sec- tions of the particular specimen illustrated in figure 167 show unusually large and few acanthopores, but other sections of the same example show them of the more usual size and number. Occurrence.—Common in the Black River (Decorah) shales of Minnesota; apparently rare in the Wassalem bed (D3) at Uxnorm, Esthonia. Plesiotype.—C&t, No. 57383, Thin
. Bulletin - United States National Museum. Science. 280 BULLETIN" 11, UNITED STATES NATIONAL MUSEUM. from American are shown in figure 168 for comparison with the Russian specimens referred to the variety. The thin sec- tions of the particular specimen illustrated in figure 167 show unusually large and few acanthopores, but other sections of the same example show them of the more usual size and number. Occurrence.—Common in the Black River (Decorah) shales of Minnesota; apparently rare in the Wassalem bed (D3) at Uxnorm, Esthonia. Plesiotype.—C&t, No. 57383, Thin sections of the Russian example are in the collections of the British Museum,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States National Museum; Smithsonian Institution; United States. Dept. of the Interior. Washington : Smithsonian Institution Press, [etc. ]; for sale by the Supt. of Docs. , U. S. Govt Print. Off.
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
