Keywords: Walcott Cambrian Geology and Paleontology II plate 31.jpg Plate 31 Middle Cambrian Crustaceans Hymenocaris and Leanchoilia 1 Hymenocaris perfecta <small>Walcott</small> 2 Hymenocaris perfecta <small>Walcott</small> 3 Hymenocaris perfecta <small>Walcott</small> 4 Hymenocaris perfecta <small>Walcott</small> 5 Hymenocaris perfecta <small>Walcott</small> 6 Hymenocaris perfecta <small>Walcott</small> 7 Leanchoilia superlata <small>Walcott</small> Charles D Walcott Middle Cambrian Branchiopoda Malacostraca Trilobita and Merostomata Smithsonian Miscellaneous Collections Volume 57 Number 6 Publication 2051 City of Washington Published by the Smithsonian Institution March 13 1912 1912 Creator Charles Doolittle Walcott PD-old-80 Walcott Cambrian Geology and Paleontology II plates Walcott Cambrian Geology and Paleontology II plates missing identification |