May, 1906.] 
Key~to Liverworts. 
531 
4. Thallus simple or slightly lobed; involucre short, lacerate; pedicel 
not folded upon itself. pinguis Dumort. 
Thallus irregularly lobed; involucre none; pedicel 16-25 mm. long, 
sometimes folded upon itself and remaining within the cal- 
yyhra, the capsule thus appearing sessile. sessilis, Spreng. 
Aiilhoccros Micheli. 
Thallus papillose; spores black, strongly muriculate and sharply 
angled. punctaUis L. 
Thallus smooth ; spores nearly smooth, yellow, angular, lacvis L. 
A.stcrclla Beauv. 
Thallus forking and increasing by joints. Antheridia in sessile 
lunate disks. Peduncle bearded at base and apex. Spores 
large, tuberculate, nearly reticulately folded. 
hemisphacrica Beauv. 
Hazzania S. F. Gray. 
Plant robust; leaves from green to brownish, about 2 mm. long, 
somewhat deflexed with concave base, their apex 3-toothed; 
underleaves roundish— quadrangular, 4^6 toothed above and 
sinuate on the sides. trilobata S. F. Gray. 
Plant much smaller; leaves yellowish or dark brown, about 1 mm. 
long, strongly deflexed, perfectly convex, their apex 2-3 
toothed or entire; underleaves suborbicular, bifid, crenate or 
entire. deflexa Underw'. 
Blasia Micheli. 
Thallus simple or forked or stellate, with sinuous margin; fruit 
from an oval cavity in the costa; involucre mostly none; 
capsule oval-globose; gemmae globose in flask-shaped recep- 
tacles; the scale-like underleaves broad-oval, coarsely dentate, 
in one longitudinal row. pusilla L. 
Hlcpliarostoma Dumort. 
Stem flaccid, creeping, branched; leaves much smaller than the 
ramose, forking and awl-shaped involucral leaves; perianth 
ovate-cylindric. trichophyllmn Dumort. 
Ccphalozia Dumort. 
1 . Perianth more or less 3-angled or 3-carinate ; leaf cells large 
(mostly 2.5-50 /x. broad;) plants medium sized. 2. 
Perianth 3-6 angled; leaf cells small (14— 20/x broad) ; plants small, 
often minute. 7. 
2. Underleaves rarely present, except on fruiting branches. 3. 
Underleaves usually present; leaves rarely subimbricate. 
fluitans Spruce. 
3. Leaf lobes straight. 4. 
Leaf lobes connivent or incurved. 5. 
4. Dioecious, rarely monoecious; without runners; usually pale; leaf 
cells opaque; perianth large, widest above middle, unequally 
ciliolate. virginiana Spruce. 
Monoecious; with runners; usually greenish or reddish; leaf cells 
pellucid; perianth linear-prismatic or fusiform, whitish, den- 
ticulate or ciliate. bicuspidata Dumort. 
5. Lcaflobes narrow, incurved. cnrvifolia Dumort. 
Leaflobes broad, short, connivent. 6. 
6. Leaves deucrrent; perianth linear-fusiform, 3-plaited, when }’oung 
triangular only above, when mature. multiflora Spruce. 
Leaves not decurrent; perianth large, oblong-cylindric, obtusely 
angled. planiceps Underwood. 
7. Growing on the ground and on rocks; heteroecious; perianth linear 
or narrowly fusiform, prismatic, denticulate or subentire; 
leaves somewhat distant with acute lobes and an almost rec- 
