May, 1906.] 
Key to Liverworts. 
533 
Perianth rough with tubercles or scales or smooth; leaves not 
marked by moniliform cells; lower lobe helmet-shaped, some- 
times expanded, ovate— lanceolate. 4. 
2. Leaves orbicular. 3. 
Leaves oblong from a narrowed base; lower lobe oblong-galeate. 
jragilifolia Tayl. 
3. Pinnate; lower lobe near stem, oblong-clavate; underleaves ob- 
long, 2-cleft, flat. Asagrayana Mont. 
Bipinnate; lower lobe distant from stem, oval or oblong; under- 
leaves quadrate-ovate or obovate, emarginate, margin revo- 
lute. Tamarisci Nees. 
4. Lower leaf lobe about ^ the size of the upper. Oakesiana Aust. 
Lower leaf lobe much smaller than the upper. .5. 
5. Underleaves scarcely wider than the stem, bifld, divisions entire, 
acute. 6. 
L^nderleaves 2-3 times wider than the stem, bifld, divisions entire 
or toothed, acute or blunt. 7. 
6. Perianth pyriform, slightly compressed, repand, smooth, obscurely 
carinate beneath and gibbous toward the apex. 
Eboracensis Lehni. 
Perianth broadly oblong, bowl-shaped with very short mouth, 
papillose, abruptly broad-carinate beneath, 1-many-nerved 
each side of the keel, 2-angled. saxicola Aust. 
7. Leaves lax, rather distant, lower lobes mostly expanded, ovate- 
lanceolate. Sporogonium unknown. acolotis Nees. 
Leaves crowded or close-imbricate, lower lobe seldom expanded. 
Sporogonium known. 8. 
8. Perianth tuberculate. 9. 
Perianth smooth. 10. 
9. Irregularly branching; leaves ovate, lower lobe sometimes expand- 
ed into a lanceolate lamina; underleaves not toothed: perianth 
compressed pyriform, 2-4 carinate dorsally, 4-carinate ven- 
trally. Virginica Lehm. 
Pinnately branching; leaves round, lower lobe not expanded: un- 
derleaves toothed: perianth obovate, retuse. dilatata Nees. 
10. L'nderleaves cordate or rounded, sinuate-subdentate; perianth 
convex dorsally, strongly keeled ventrally. sqitarrosa Nees. 
Underleaves rather large, rounded; perianth sulcate dorsally, 
acutely keeled ventrally. plana Sulliv. 
Gcocalyx Nees. 
Stem creeping with numerous rootlets; leaves ovate-quadrate, 
bidentate, light to bluish green; underleaves cleft to the 
middle, with linear-lanceolate divisions. graveolcns Nees. 
Grimaldia Raddi. 
Thallus pale green, purple on the margin and below, with usually 
distinct whitish pores, the scales beneath often extending far 
beyond the margin and becoming whitish; peduncle barbed 
whitish and chaffy at base and apex. harbifrons Bisch. 
Thallus bluish-green with membranous margins, purple below; 
])cduncle sparingly scaly at base, barbulate at the apex. 
rnpcstris Lindenb. 
Gymnomitrium f'orda. 
Stem simple or imbricately branching, thickened at the apex; 
leaves ovate, bifid, with a narrow scarious margin, bluish- 
green or brownish- or reddish-yellow to silvery-olive; no un- 
derleaves. concinnatmn Corda. 
Harpanthns Nees. 
Stem filiform, decumbent, usually simple, leaves roundish ovate, 
their lobes acute; underleaves large, nearl)’ 3-sided-lanceolate, 
mostly entire; perianth splitting above on one side. 
scutatus Spruce. 
