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  • Periarchus lyelli


    sixgill pete


    Sand Dollar

    Kingdom: Animalia
    Phylum: Echinodermata
    Class: Echinoidea
    Order: Clypeasteroida
    Family: Protoscutellidae
    Genus: Periarchus
    Species: P. lyelli
    Author Citation (Conrad, 1868)

    Geological Time Scale

    Eon: Phanerozoic
    Era: Cenozoic
    Period: Paleogene
    Epoch: Eocene
    Age: Priabonian


    Castle Hayne Formation
    Comfort Member


    Collector: Don Rideout
    Date Collected: 11/07/2014
    Acquired by: Field Collection


    Length: 25.7mm
    Width: 24.8mm
    Thickness: 3.6mm


    Martin Marietta Quarry
    New Hanover County
    North Carilina
    United States


    Collected at the Martin Marietta Castle Hayne Quarry. This is a very common find, though most are limestone or marl encrusted or broken. P. lyelli is found in Zullo & Harris, 1987 sequence 4 of the Castle Hayne (Kier, 1980 middle to late biozone). A very similar species; Periarchus sp. is found in Sequence 3. P. lyelli is most easily identified and differentiated from Protoscutella and Periarchus sp. by the placement of the periproct. The periproct is located slightly above the central point between the peristome and the posterior margin of the test.   

    User Feedback

    Interesting, I never noticed that Periarchus had the furrows around the tubercles. I don't think any of mine from MS show them. I probably would have labeled this as Clypeaster rogersi :mellow:

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