Plants very small, delicate, pale green, loosely gregarious. Leafy stems simple, 1.2–3.2 mm long, 0.8–3.0 mm wide; axillary hyaline nodules not differentiated; central strand lacking. Leaves in 2–5 pairs, densely arranged, upper leaves much larger than lower leaves, oblong-lanceolate to oblong-ovate, 0.6–1.4 mm × 0.2–0.6 mm, acute at the apex; base of dorsal laminae rounded, vaginal laminae nearly 1/2 the leaf length; costa absent; margins plane, entire, bordered throughout by 1–2 rows of elongate cells; cells of apical laminae quadrate to irregularly hexagonal, 35–87 µm long, smooth, thin-walled; cells of vaginant laminae similar to those of apical laminae. Sporophytes unknown.

Type. U.S.A.: Ohio, T. G. Lea s.n. (isotype NY).

Chinese specimens examined: JILIN: Jiao-he Co., X.-G. Kang 00004 (IFSBH). TAIWAN: Tai-zhong Co., Iwatsuki & Sharp 3187 (NICH). YUNNAN: Kun-ming City, Redfearn et al. 2178 (MO).

Habitat: on moist rocks; Distribution: China, Japan, India, North and South America.

Fissidens hyalinus is extremely small and is not easy to locate without keen eyes and experience. It is always found on newly eroded soil banks in shaded sites.

Illustrations: Z.-H. Li 1985 (Fig. 1, a–g).