[*] Underleaves rarely present except on fruiting branches.
1. C. Virginiàna, Spruce. Without runners, usually pale; leaves small, obliquely round-ovate, acutely 2-lobed nearly to the middle; cells quadrate-hexagonal, opaque; diœcious, rarely monœcious; involucral leaves round-quadrate, with slender acuminate lobes; perianth large, widest above the middle, unequally ciliolate; capsule large, long-exserted; antheridial spike long. (C. catenulata of authors; not Huebn.)—On rotten wood or swampy ground, N. Eng. to Va., and southward.
2. C. multiflòra, Spruce. ([Pl. 23.]) Often subpinnate, without runners, pale green; leaves small, round-rhombic, decurrent, bifid {1/3} their length; cells quadrate-hexagonal, pellucid; diœcious; inner involucral leaves 3–4 times as long as the outer; perianth linear-fusiform, 3-plaited when young, triangular only above when mature, ciliate or toothed, fleshy; calyptra fleshy, oval-globose; capsule rather short-pedicelled; spores cinnamon-color.—On the ground and rotten wood; common. (Eu.)
3. C. pléniceps, Underw. Stems very short, branching, densely cespitose, pale green or whitish; leaves thick, orbicular, strongly concave, subclasping but not decurrent, bifid {1/3} their length, the acute lobes incurved and strongly connivent; involucral leaves oblong, palmately 2–4-cleft, the ventral like the underleaves; perianth large, oblong-cylindric, obtusely angled, the plicate mouth denticulate. (Jungermannia pleniceps, Aust.)—Among Sphagnum in the White Mts. (Oakes).
4. C. bicuspidàta, Dumort. Prostrate or assurgent, cespitose, usually greenish or reddish, with runners; lower leaves small and distant, the upper larger, round-ovate, cleft nearly to the middle, the lobes ovate-lanceolate and acute, the lower lobe narrower and acuminate; cells large, pellucid; monœcious; involucral leaves about 3 pairs, the innermost nearly three times as long as the outer, cleft ½ their length; perianth four times as long as the leaves, linear-prismatic or fusiform, thin, denticulate or ciliate; capsule cylindric-oblong; spores purple. (Jungermannia bicuspidata, L.)—On the ground, mountains of N. Eng., N. Y., and N. J. (Eu.)
5. C. curvifòlia, Dumort. Slender, rarely forked, without runners, greenish, reddish, or often purple; leaves imbricate, ascending, obovate, concave, semicordate at base, lunately bifid below the middle, the lobes incurved or hooked; cells small, quadrate; monœcious or diœcious; involucral leaves complicate, the lobes subovate, spinulose-denticulate; perianth large, rose-purple, triquetrous, the wide mouth ciliate; calyptra thin; capsule oblong-globose. (Jungermannia curvifolia, Dicks.)—On rotten logs in swamps, etc.; common. (Eu.)
[*][*] Underleaves usually present; leaves rarely subimbricate.
6. C. flùitans, Spruce. Stems 2–3´ long, loosely creeping, with short thick runners; leaves large, ovate-oblong, lobed to near the middle, the lower lobe larger, lanceolate, obtuse; cells large, mostly hexagonal; underleaves linear, appressed; diœcious; involucral leaves cleft to the middle; perianth oval-cylindric, nearly entire; calyptra short, pyriform; capsule oblong; spores small, minutely tuberculate; antheridia globose, pedicelled, solitary in the axils.—In bogs, on mosses or partly floating; rare. (Eu.)
§ 2. CEPHALOZIÉLLA. Perianth 3–6-angled; leaf-cells small (14–20 µ broad); plants small, often minute; underleaves present in n. 9.
7. C. divaricàta, Dumort. Sparingly branched, without runners; leaves very small, cuneate or round-quadrate, the ovate-triangular lobes acute; cells pellucid or subopaque; involucral leaves larger, the lobes acute, denticulate; perianth linear or narrowly fusiform, prismatic, denticulate or subentire; capsule oblong-globose, long-exserted. (Jungermannia divaricata, Smith.)—Dry rocks and sand, pine barrens of N. J., and northward. (Eu.)