File:North American index fossils, invertebrates (1909) (14594452398).jpg

Identifier: northamericanind02grab (find matches)
Title: North American index fossils, invertebrates
Year: 1909 (1900s)
Authors: Grabau, Amadeus W. (Amadeus William), 1870-1946 Shimer, Hervey Woodburn, 1872-1965
Subjects: Paleontology Invertebrates, Fossil
Publisher: New York : A.G. Seiler
Contributing Library: California Academy of Sciences Library
Digitizing Sponsor: California Academy of Sciences Library

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g ven-trally. A ventrally adjacent plate of one of the bounding columnsis characteristically seven-sided. Newly added plates dorsally aremore or less rhombic in Outline. This facilitates the orientationof obscure fragments. Mississippic. 14. M. multiporus Norwood and Owen. (Fig. 1917, a-c.) Mississippic. With ten ambulacral and seven to eight or nine interambulacralcolumns of plates. The most characteristic fossil of the St. Louis limestone ofMissouri, Indiana, Tennessee, Kentucky, etc. VIII. Lepidesthes Meek and Worthen.Large; plates of corona regular and imbricated; interambulacrafrom 3-7 columns, imbricating aborally and laterally; ambulacrabroad, from 8-18 (or perhaps 20?) columns, imbricating adorallywith pores in center of plates. Mississippic. 15. L. wortheni Jackson. (Fig. 1917, J.) Mississippic.With seven to eight columns of ambulacra in adult and interam- 584 NORTH AMERICAN INDEX FOSSILS. bulacra beginning as four, but subsequently reduced to threecolumns. Keokuk of Indiana.
Text Appearing After Image:
Fig. 1917. a-c, Melonites muliiporus, a part of corona from oral or ventral end,showing two columns at peristome (^, C and /) and three ^E, G). Amb. 4. If,dorsal portion of interambulacrum, and the separation of plates in columns. The fullnumber of columns is shown by plates along line, X- V. a, genital plates, with 3 or 4pores; 0, imperforate ocular plates, X ^/^ > ^t spines, X 4 > ^> Lepidesthes wortheni,a crushed specimen, X I/^/showing broad amb. area and 4 (later 3) interamb.; D.D,dental pyramids ; e, Lepidechinus rarispinus, oral aspect, showing single interamb. in-creasing to 8, X iK- (After R. T. Jackson and T. A. Jaggar, Jr ) 16. L. colletti White. Mississippic. With 18 (or 20?) ambulacral, and 4-5 interambulacral columns.Keokuk of Indiana. ECHINODERMA TA—ECHINOIDEA. 585 IX. Pholidocidaris Meek and Worthen. With coarse, highly irregular, imbricating interambulacral plates,of which it has five or more columns; and six or more columnsof irregular, much smaller ambula

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