The genera Meteoridium and Zelometeorium are described and illustrated from 73 collections made by the author in Bolivia. Barbella tenuissima (Hook. & Wils.) Fleisch. is transferred to the genus Meteoridium as Meteoridium tenuissimum (Hook. & Wils.) M. Lewis comb. nov. Due to its hypnobryoid peristome and other characters, the genus Meteoridium is placed in the Brachytheciaceae. Meteoridium remotifolium (C. Müll.) Manuel shows marked variation over its altitudinal range and four ecoforms are

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... ognized. Distribution records show that the species of these two genera have distinct ranges, with only Meteoridium remotifolium overlapping the ranges of the other species. Habitat data shows that none of the species treated are obligate epiphytes, and that they grow equally well in terrestrial habitats. The genus Meteoriopsis was revised by Manuel (1977a Manuel ( , 1977b and the South American species were divided amongst two genera: Meteoridium and Zelometeorium. In Manuel's revision, few localities were given for Bolivia, and the habitat information proved scanty. I had noticed during rough sorting of my specimens that the species seemed to have distinct ranges in Bolivia and that many populations were not epiphytic, but were found on loose sticks and twigs, the sides of cliffs, and even over humus covered boulders. I also noticed that some species varied considerably over their range. In order to document these phenomena, I examined 73 collections of the genus Meteoriopsis sensu lato that I made over the years in Bolivia. For each collection, the following data were recorded: collection number, locality, altitude, habitat, substrate, leaf shape and insertion, leaf width and length; shape, length and width of alar, basal, mid and apical leaf cells ; form of cell walls of alar, basal, mid and apical leaf cells; costa length -leaf length ratio, widest point of leaf -leaf length ratio; flagelliform branch presence or absence, and costal anatomy. Measurements were made averaging 25 leaves, or 5 cells each from 5 leaves for each collection number. This information was placed in tabular form to see what, if any, variation occurred. Sporophytes of these genera are exceedingly rare, and were examined when available. Illustrations were made using a Leitz Mikro Promar microprojector and descriptions were then written using the data from the tables. Identification using Manuel's revisions were then made, and confirmed by comparison with specimens at the New York Botanical Garden. The results are presented below. Collection numbers are those of the author unless otherwise noted, and all specimens are deposited in LPB with some duplicates at F and MO.