1903] ODONTOSCHISMA MACOUNIT AND ITS ALLIES 339 
4. Plants commonly brownish green, leaves broadly orbicular, usually 
erect and connivent simi ee pang! more than one cell 
wide - - 4. O. Sphagni 
4. Plants pale green, more mele desea with brownish, pales varying from 
oblong to orbicular but usually longer than broad, mostly explanate, 
margin from one to four cells wide - - - 5. O. prostratum 
1. Opontoscuisma Macouni ( Aust.) Underw. Bull. Ill. State 
Lab. Nat. Hist. 2: 92. 1884—Plate XVIII. 
Sphagnoecetis Macounii Aust. Bull. Torr. Bot. Club 3: 13. 
Sphagnoecetis communis, var. tessellata Berggr. Kongl. Se Vet Akad. 
Handl. 137: ror. 1875. 
Jungermannia tessellata Berggr. 7. c. 13°: 43. 1 
Cephalozia (Odontoschisma) Austini Pears, List Canad. Hepat. 10. 1890. 
Odontoschisma Sphagni, var. tessellatum Kaalaas, Vidensk. Skrift. I. 
18989; 14. 
Odontoschisma tessellatum C. Jensen, Meddel. om Grenland 15: 369. 
SJ. I-g. 1898. 
Plants pale green or yellowish, rarely tinged with brown, 
growing in depressed mats or creeping among other bryophytes: 
stems sparingly and irregularly branched, 0.2™" in diameter, 
prostrate, ascending at the tips; flagella postical, with very 
minute and rudimentary leaves; vegetative and sexual branches 
varying from postical to lateral, but usually occupying the latter 
position; rhizoids scanty, borne either on the flagella or on the 
postical surface of the stem and leafy branches, never on the 
underleaves: leaves imbricated, strongly concave, broadly orbicu- 
lar, 0.75™™ long, 0.85™™" wide, not margined, attached by an 
oblique line of insertion, neither dilated at the postical base nor 
decurrent antically, margin entire, apex varying from broadly 
rounded to truncate or slightly retuse, very rarely indistinctly 
bilobed: leaf cells 254 in diameter at the margin of leaf, 28h 
in the middle and at the base, with very large, occasionally 
confluent and rounded trigones; cell cavities stellate with 
narrow pits; cuticle very thick, smooth: underleaves varying 
from minute to rather large, reaching a maximum length of 
about 0.2™", when well developed ovate to oblong in shape, 
rounded, retuse or irregularly bilobed at the apex, margin entire, 
but bearing numerous slime-papillae: inflorescence dioicous: ¢ 
inflorescence borne on a short branch; involucral leaves (bracts 
