AbstractIn theory, the E-W location and high elevation of the Neovolcanic Belt have reduced floristic flow between parts of northern and southern Mexico. However, this barrier effect is not complete, as may be inferred from the distribution of moss taxa in adjacent areas. Migration across the Neovolcanic Belt may account for the presence of many moss species on either side of this mountain range. Moss exchange may take place through topographic discontinuities herewith designated as floristic corridors. There are at least seven such inland corridors as well as the two coastal plain areas. The latter are probably very important in the latitudinal distribution of lowland species from the tropics northward. The moss flora of the Tuxpan corridor in Michoacan includes lowland species and corridor taxa which have reached or crossed the Neovolcanic Belt from the south if of tropical derivation. The remaining mosses are high elevation species or taxa of broad altitudinal distribution which have spread along the mountains.