538 The Ohio Naturalist. [Vol. VI, No. 7, 



Thallus distinctly cc state. Calyptra not surpassing the invokicre. 



Antheridia on a separate thallus. 2. 



2. Divisions of thallus broadly linear, the margin mostly undulate 



cri sped . cndiviacfolia D umc rt . 



Divisions of thallus, the early ones linear-oblong, the margins 



ascending and remotely sinuate, the later ones linear-pinna- 



tihd. calycina Nees. 



Plagiochila Dumort. 



1. Leaves with 3-12 large, spinulose and distant teeth; no under- 



leaves. spinulosa Dumort. 



Leaves entire, repand or denticulate. 2. 



2. Lower part of stem leafy to the base; underleaves 2-3 ceft, fuga- 



cious. 3. 

 Lower part of stem, forining a rhizome, bearing scales; no under- 

 leaves; mouth of perianth ciliate. asplcnioidcs Dumcrt. 



3. Leaves entire or slightly repand; mouth of perianth crenulate. 



intcrrupta Dumcrt . 

 Leaves entire, the uppermost repand-denticulate; mouth of peri- 

 anth denticulate. porelloidcs Lindenb. 

 Porclla Dill. 



1. Stems bipinnate; leaves more or less remote, ovate-oblong, lower 



lobe minute, flat, as long but not half as wide as the ovate- 

 rectangular entire underleaves. pinnata L. 

 Stems mostly simply pinnate (or bipinnate in P. platyphylla) ; 

 leaves mostly closely imbricate, round-ovate or ovate. 2. 



2. Leaves sub-erect, the straight ventral margin strongly involute 



towards the apex; cells punctate-stelliform. 



Snllivantii Underw. 

 Leaves flat or more cr less concave at base cr somewhat convex, 

 the margin decurved cr curved upwards. 3. 



3. LTpper leaf-margin curved upwards and undvilate, mcstly entire; 



lower lobe reaching half of upper, hardly deucrrent; under- 

 leaves semi-circular with strongly reflexed margins, entire. 



platyphylla Lindb. 

 Upper leaf inargin decurved, mere or less denticulate; lower lobe 

 smaller, long-decurrent ; underleaves suborbicular or quad- 

 rate-oval or rjuadrate, dentate cr ciliately .serrate. 4. 



4. Underleaves suborbicular or quadrate-oval, the margins undu- 



late and dentate; lower lobe acute, reaching \ of upper and 

 half as wide as the dentate underleaves. dcntata Lindb. 



LTnderleaves quadrate, the margins sparsely dentate; lower lobe 

 oblong, obtuse, longer but narrower than the underleaves, 

 both with strongly recurved and sparsely denticulate margins. 



Thuja Lindb. 

 Prctssia Nees. 



Thallus large, sparingly forking, increasing by joints, ends of lobes 



subcordate, with white pores above and dark purple scales 



below. Antheridia in a pedvmcled disk-like receptacle. 



Dioecious or usually monoecious. comniiitata Nees. 



Ptilidiiim Nees. 



Stem subpinnate with short rootlets; perianth several times longer 

 than the involucre. Antheridia in the base of clcsely imbri- 

 cated leaves. Dioecious. ciliarc Nees. 

 Radttla Dumort. 



L Lower lobe small, rounded, mf)rc or less transversely adnate. 



fcnax Lindb. 

 Lower loT)e suVxnuidrate, barely incumbent on the stem. 2. 

 2. Widely subi)innately branched; leaves imbricate, rounded; peri- 

 anth obconic, coinpressed. Antheridia in the bases of 2-3 

 ])airs of strongly imliricate tmnid leaves, coinplanata Dvmiort. 



