original descriptionConrad, T. A. (1838-1839). Fossils of the medial Tertiary of the United States. No. 1. Judah Dobson, Philadelphia, pp. i–xvi, 1–32 + covers with text., available online athttps://books.google.de/books?redir_esc=y&hl=de&id=5vYyAQAAIAAJ page(s): 17 [p. 35 of reprint] [details]