Micronesia includes a vast area comprised of numerous tiny land masses in the western tropical Pacific Ocean. The area includes the Bonin (B), Volcano (V), Mariana (M), Palau (P), Yap (Y), Caroline (C), Marshall (Ms), and Gilbert (G) island groups. Many of the islands are low, arid atolls with a limited bryoflora, but the high islands, e.g., Guam, Yap, Palau, Ponape, and Kusaie, appear to support a rich bryoflora in wet mountaintop forests. The first bryophyte collections were made between 1817 and 1820 by Charles Gaudichaud in the Mariana Islands-principally in Guam. These collections were reported by Schwaegrichen (1811-42) and by Gaudichaud (1828) himself. Bory de St. Vincent (1827-29) reported a number of cryptogams collected on Guam and Oualau (Kusaie) during the visit of the Coquille between 1822 and 1825. Mertens (1835) visited the Caroline Islands on the Seniavine and collected several species of Hepaticae reported in the Synopsis Hepaticarum and some mosses. These three collections appear to be the basis for most of the reports of Micronesian bryophytes until the latter part of the 19th century. Small but important additional collections were listed by Stephani (1900-24, 1902), Brotherus (1898, 1902, 1924-25), and Dixon (1927, 1928). In 1929, Horikawa began a series of publications dealing with the Hepaticae of Japan and Micronesia with the result that many new species were described. During World War II, important papers were contributed by Sakurai (1943), Dixon (1943), and Bartram (1945). Over the past ten years, lists by Andrews (1951), Glassman (1952), Miller (1953, etc.), Moul (1957, 1958) and Inoue (1959) have substantially increased the number of reported species. Inasmuch as these reports are widely scattered and not easily assembled, the following list has been prepared to serve as a base for further study of Micronesian bryophytes. No attempt has been made to provide full synonymy because published reports can be based on misidentifications and voucher specimens have not yet been seen. Island groups are indicated by the letters inserted in the introductory paragraph, and there has been no attempt to