The writing of this paper would have been impossible without the generous and whole-hearted coöperation of many institutions and individuals. This assistance has ranged from the furnishing of specimens for determination, to advice as to methods, classifications, and the supplying of modern material for comparison. For specimens of classified plants to be used in the comparative work thanks are due to The New York Botanical Garden in Bronx Park, the Botanical Departments of the University of Wisconsin, the University of Oklahoma, and the University of Georgia. The standard histological microscopic methods were used for the determination of the fiber. Slides were made of both cross-sections and longitudinal sections and these were compared with previously prepared and classified modern material. When the specimen was too colored for microscopic examination it was bleached in a solution of Sodium perborate until clear enough for study. In charred material, when sufficient detail was preserved for identification the fiber sample was treated with Schultz Maceration solution, washed, dried, and fortified by saturating in a collodion solution. Occasionally, it was found necessary to stain the material and in this either Delafield's Haematoxylon or Methylene Blue was used. In the differentiation of certain species, it was found necessary to make microscopic measurements of the length and width of the cells, but generally the shape, distribution, medullation, and other constant characters were sufficient for the identifications. In the text and tables the following abbreviations are used for the names of the coöperating institutions:-- American Museum of Natural History AMNH Museum of the American Indian, Heye Foundation MAIHF Milwaukee Public Museum MPM McGill University Archaeological Museum McGU Ohio State Historical and Archaeological Museum OSHAM Peabody Museum, Harvard University PMHU Rochester Museum of Arts and Science RMAS University of Kentucky Museum UKM United States National Museum USNM MONOCOTYLEDONOUS SPECIES The fibers from monocotyledonous plants, as identified, are listed here. Approximately five hundred objects were sampled, so the frequencies for the several species should be given that denominator. ARECACEAE, Reichenb. (Palm Family)