The development of gametophytes in Bolbitis bernoullii, B. portoricensis and B. umbrosa (Lomariopsidaceae) is described and compared. Spores are monolete, ellipsoid with prominent winged perispore. Germination is of the Vittaria type and the prothallial development is of the Drynaria type. Collenchyma-like thickenings at the corners of the wing cells were not observed. Adult gametophytes are cordate with scarce marginal hairs near the shallow notch. Gametangia are of the common type found in homosporous leptosporangiate ferns. Bolbitis portoricensis develops the first leaf of the sporophyte after 6 to 8 months, with polocytic stomata. In B. portoricensis, vegetative propagation is present in old thalli 6 to 8 months after cultivation. The genus Bolbitis is a terrestrial or hemiepiphyitic fern, with dimorphic leaves and simple or pinnate blades. Some species have laminar buds, and all have fertile leaves with acrostichoid sori, and reticulate venation with or without included veinlets. Its spores are monolete, non-chlorophyllous, and winged (Mickel and Smith, 2004; Moran, 1995; Tryon and Tryon, 1982; Tryon and Lugardon, 1991). The genus contains about 45 species, a third of which are found in the New World; seven occur in the southeastern part of Mexico. These seven species grow between 0-1300 masl in very wet rainforests. Except for B. portoricensis (Spreng.) Hennipman, all species are uncommon or rare in Mexico. The gametophyte morphologies are known for several Indian species: Bolbitis semicordata (Moore) Ching, B. quoyana (Gaud.) Ching, B. subcrenata (Hook. et Grev.) Ching in C. Chr. (Nayar, 1960; Nayar and Kaur, 1964a, 1964b, 1965a, 1965b, 1965c, 1971); and for Old Word species such as B. angustipinna (Hayata) Ito, B. heteroclita (Presl) Ching and B. repanda (Bl.) Schott (Hennip- man 1970, 1977). In general terms, the mature prothallus of Bolbitis is cordate- thalloid, wider than long, with a dense, 6 to 8-celled thick cushion, and wide flat wings. Collenchyma-like thickenings are present in the corners of wing cells of some Indian species. Gametophytes of Bolbitis can be morphologically different. For instance, the prothallus in B. repanda is cordate, with pluricellular branched hairs and, when old, has a lobed thallus. In B. cladorrhizans (Spreng.) Ching, the gametophyte is glabrous and ribbon-shaped or lobed. Other species such as B. heteroclita have cordiform-spatulate prothalli, with unicellular, secretory and papillate hairs sparsely distributed along the margin of the adult gametophyte. In species such as B. semicordata, B. quoyana and B. subcrenata, the adult cordate thallus is usually branched but may be un-branched and has club-