Keywords: Walcott Cambrian Geology and Paleontology II plate 13.jpg Plate 13 Middle Cambrian Holothurians Laggania Mackenzia and Louisella 1 Laggania cambria <small>Walcott</small> 2 Mackenzia costalis <small>Walcott</small> 3 Mackenzia costalis <small>Walcott</small> 4 Louisella pedunculata <small>Walcott</small> Charles D Walcott Middle Cambrian Holothurians and Medusae Smithsonian Miscellaneous Collections Volume 57 Number 3 Publication 2011 City of Washington Published by the Smithsonian Institution June 13 1911 Creator Charles Doolittle Walcott 1911 PD-old-80 Walcott Cambrian Geology and Paleontology II plates Walcott Cambrian Geology and Paleontology II plates missing identification |