3. M. hamata, Lindb. Like the last; thallus much elongated (4' long, 1--1" wide); hairs very long, divaricate and hooked-deflexed, the marginal in twos, rarely with discoid tips; midrib covered above and below with two rows of enlarged lax cells. (M. furcata, _Sulliv._, in part.)--Alleghany Mts. (_Sullivant_).

4. M. conjugata, Lindb. Thallus 1' long, --1" wide, usually dichotomous, the short branches irregular in width, convex above, the margins more or less undulate; hairs rather long, straight, divaricate, the marginal usually in twos, very often disk-bearing; midribs covered above with 2, below with 3--6 rows of enlarged lax cells.--On shaded rocks and trunks of trees, central N. Y., and southward. (Eu.)

33. ANEuRA, Dumort. (Pl. 23.)

Thallus fleshy, prostrate or a.s.surgent from a creeping base; costa obscure. Dicious or moncious. Fructification arising from the under side near the margin. Involucre cup-shaped, short and lacerate, or none.

Calyptra large, fleshy, more or less clavate. Capsule large, oblong-cylindric. Elaters unispiral, in part adherent to the tips of the valves. Spores minute, smooth or minutely roughened. Antheridia immersed in the surface of receptacles proceeding from the margin of the thallus.

(Name from a- privative, and ?e????, a nerve.)

[*] _Thallus narrow (about 1" wide), palmately divided._

1. A. latifrons, Lindb. Thallus cespitose, ascending or erect, usually dark green, 6--9" long, mostly pellucid; branches linear, obtuse and emarginate, plano-convex; cells large, oblong-rhombic; moncious; archegonia 3--10, short, conic; calyptra white, verrucose, pyriform-clavate; capsule oval, brown; spores 12--14 broad, globose, minutely and densely papillose; antheridia globose. (A. palmata of authors; not _Dumort_.)--On rotten logs; common.

[*][*] _Thallus narrow (about 1" wide), pinnate or bipinnate._

2. A. multifida, Dumort. Thallus prostrate, brownish-green, pinnately divided, the primary portion biconvex, somewhat rigid, the branches horizontal, pectinately pinnate with narrow linear divisions; moncious; fructification rising from the primary part or from the branches; involucre fleshy; calyptra tuberculate.--Var. MaJOR, Nees. Primary portion and branches thick, the branches interruptedly pinnate with short obtuse divisions.--On decayed wood and moss in swamps, N. J.

(_Austin_), and south in the mountains. (Eu.)

3. A. pinnatifida, Nees. Thallus pinnately divided or subsimple, flat or somewhat channelled; branches horizontal, the broader pinnatifid or dentate, obtuse; calyptra somewhat smooth.--On dripping rocks, Hokokus, N. J. (_Austin_), N. Haven, Conn. (_Eaton_). (Eu.)

[*][*][*] _Thallus wider (2" or more), simple or irregularly lobed._

4. A. sessilis, Spreng. Thallus dec.u.mbent, irregularly lobed, 1--2'

long, 3--5" wide; involucre none; pedicel --1' long, sometimes folded upon itself and remaining within the calyptra, the capsule thus appearing sessile; antheridia on elongated receptacles.--Wooded swamps.

Elongated floating forms, 5--6' long, have been found in the White Mts.

(_Farlow, Faxon_).

5. A. pinguis, Dumort. Thallus 1--2' long, dec.u.mbent or ascending, fleshy, linear-oblong, simple or slightly lobed, the margin sinuate; dicious; involucre short, lacerate; calyptra cylindric, smooth; capsule brownish, furrowed; antheridia in 2-lobed receptacles.--Wet banks, N. J.

to Ohio, and southward. (Eu.)

ORDER 138. ANTHOCEROTaCEae. (HORNED LIVERWORTS.)

Plant-body a thallus, irregularly branching, flaccid, without epidermis or pores, and more or less vesiculose. Involucre single, tubular.

Calyptra rupturing early near the base, and borne on the apex of the capsule. Capsule dorsal, pod-like, erect or curved outward, more or less perfectly 2-valved, usually stomatose, tapering into a pedicel or often sessile with a bulbous base. Columella filiform. Elaters with or without spiral fibres. Spores flattish, more or less convex-prismatic, papillose or smooth.

1. Anthoceros. Capsule narrowly linear, exsertly pedicelled, 2-valved.

Elaters present.

2. Notothylas. Capsule very short, sessile, not valved below the middle.

Elaters not obvious.

1. ANTHoCEROS, Micheli. (Pl. 22.)

Thallus dark green or blackish, usually depressed, variously lobed, with large chlorophyll-grains, frequently glandular-thickened at the apex or in lines along the middle so as to appear nerved. Moncious or dicious.

Capsule linear, 2-valved, exsertly pedicelled. Elaters simple or branched, often geniculate, more or less heteromorphous, the fibres wanting or indistinct. (Name from ?????, _flower_, and ???a?, _horn_, from the shape of the capsule.)

1. A. lae'vis, L. (Pl. 22.) Thallus smooth, nearly flat above; dicious; involucre 1--2" long, trumpet-shaped when dry, repand-toothed; capsule pale brown or yellowish, 1--1' long; elaters rather short, yellowish; spores yellow, nearly smooth, angular.--Wet clay banks, from Canada south and westward. (Eu.)

2. A. punctatus, L. Thallus small, depressed, or often cespitose and erect, more or less glandular; moncious; involucre rather short, oblong-linear, slightly repand, sometimes scarious at the mouth; capsule 1' high, black; elaters fuscous, flattish, geniculate; spores black, strongly muriculate, sharply angled.--Wet banks, Canada to Mo., and southward. (Eu.)

2. NOTOTH?LAS, Sulliv. (Pl. 22.)

Thallus...o...b..cular, tender, laciniate and undulate or crisped, papillose-reticulate. Moncious. Involucre sessile, continuous with the thallus, opening irregularly above. Capsule very short, oblong-globose or ovate-cylindric, pedicelled from a thickened bulb, 2-valved to the middle or rupturing irregularly. Elaters none, or fragmentary and inconspicuous. Spores subglobose, smoothish. Antheridia elliptic-globose, immersed in the thallus. (Name from ??t??, _the back_, and ?????, _a bag_, from the shape and position of the involucre.)

1. N. orbicularis, Sulliv. (Pl. 22.) Thallus 3--8" wide; capsules 1--2" long, erect or decurved, wholly included or slightly exserted, of thin and loose texture, with a suture on each side; spores light yellowish-brown. (Including N. valvata, _Sulliv._)--Wet places, Canada to the Gulf.

2. N. melanospora, Sulliv. Thallus small, depressed or sometimes cespitose, of lax texture; capsule often without sutures; spores dark brown, a half larger.--Moist ground, Ohio (_Sullivant_).

ORDER 139. MARCHANTIaCEae. LIVERWORTS.

Plant-body a thallus, dichotomous or subpalmately branching, usually innovating from the apex or beneath it, more or less thickened in the middle, and bearing numerous rootlets beneath and usually colored or imbricating scales. Epidermis usually more or less distinct and strongly porose above. Capsules globose, rarely oval, opening irregularly, pendent from the under side of a peduncled disk-like receptacle (_carpocephalum_). Elaters present, mostly 2-spiral.

[*] Thallus plainly costate, distinctly porose except in n. 6.

[+] Gemmae present on sterile stems.

1. Marchantia. Gemmae in cup-shaped receptacles. Fertile receptacle 7--11-rayed.

8. Lunularia. Gemmae in crescent-shaped receptacles. Fertile receptacle cruciform.

[+][+] Gemmae wanting.

[++] Receptacle conic-hemispherical, 2--4-lobed; perianth lobed or fringed.

2. Preissia. Receptacle 2--4-lobed, with as many alternate rib-like rays. Perianth 4--5-lobed.

3. Fimbriaria. Receptacle 4-lobed. Perianth conspicuous, split into 8--16 fringe-like segments.

[++][++] Receptacle more or less conical; perianth none.

4. Conocephalus. Thallus very large, strongly areolate. Receptacle conical, membranous.

5. Grimaldia. Thallus small. Peduncle chaffy at base and apex.

Receptacle conic-hemispheric, truncately 3--4-lobed.

6. Asterella. Thallus eporose. Receptacle conic-hemispheric, becoming flattened, acutely 4- (1--6-) lobed.

[*][*] Thallus thin, ecostate or barely costate.

7. Dumortiera. Receptacle convex, 2--8-lobed. Perianth none.

1. MARCHaNTIA, Marchant f. (Pl. 22.)