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2. Rud. Rüdemann, The lower Siluric Shales of the Mohawk Valley. New York St. Mus. Bull. 162, S. 75, T. 1, F. 9 (Albany 1912).
3. Ch.D. Walcott, Middle Cambrian Holothurians and Medusae. Cambrian Geology and Paleontology, Vol. II, Nr. 3, 1911. Smiths. Misc. Coll., Vol. 57, S. 45–55, Taf. 8–13.
4. Ch. D. Walcott, Appendages of Trilobites. Cambrian Geology and Paleontology IV, Nr. 4. Smiths. Misc. Coll., 1918, Bd. 57, S. 116–178. — Ch.D. Walcott, Notes on structure of Neolenus. ibid. IV, Nr. 7, ibid. 1921, Bd. 57, S. 365–432.
5. Ch. D. Walcott, Cambrian Geology and Paleontology II, Nr. 6, Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smiths. Misc. Coll. 1912, Bd. 57, S. 192, Taf. 25, 26.