EVANS—THE NORTH AMERICAN SPECIES OF ASTERELLA. 307 
mediate position between A. bolanderi and A. elegans. Possibly the careful 
study of these closely related species in the field will bring to light differential 
characters which the study of preserved material bas failed to show. 
15. Asterella versicolor Evans, sp. nov, 
Thallus green above, deeply pigmented with purple on the ventral surface 
and along the margin, mostly 0.5 to 1 cm. long and 1.5 to 8 mm. wide, more 
or less concave, especially when dry, the slightly crispate margins often becom- 
ing more or less incurved; branching ventral, sometimes by apical innovations, 
some of the branches growing out into narrow subterete processes with reduced 
green tissue; keel broad and rounded; epidermis composed of cells with slightly 
thickened walls and scarcely evident trigones, averaging about 45 X 80 4g; 
pores somewhat elevated, measuring (with their surrounding cells) mostly 100 
to 140 » in length and 70 to 90 uw in width, surrounded usually by 6 (rarely 5 or 
7) radiating series of cells with 2 or 8 cells in each series, the radial walls 
slightly thickened; cells with oil bodies as in A. tenella, usually forming an 
irregular row in the lower epidermis near the margin; green tissue compact, 
the air chambers in 8 or 4 layers, those of the dorsal layer larger than the 
others but subdivided by crowded vertical supplementary partitions extending 
nearly or quite to the epidermis except in the vicinity of the pores; compact 
tissue occupying about two-thirds the thickness of the thallus in the median 
portion, thinning out rather abruptly on the sides and extending from one-third 
to one-half the distance to the margin, composed of cells with thickened pitted 
walls; mycorhiza.abundant (so far as observed); ventral scales ovate, often 
pigmented throughout but sometimes with paler margins and appendages; cells 
containing oil bodies mostly 10 to 20, scattered but more abundant in the acro- 
petal portion; marginal slime papillae usually persistent; appendages borne 
singly or (rarely) in pairs, narrowly subulate, not constricted at the base but 
usually sharply marked off, mostly 0.4 to 0.6 mm. long and 0.05 to 0.07 mm. 
wide, entire, acuminate, the cells mostly 60 to 100 uw long and 30 to 35 uw wide; 
inflorescence autoicous; male inflorescence (so far as observed) borne on a 
very short expanded branch, the antheridia forming an irregular median group 
without marginal paleae, the ostioles distinct; female inflorescence borne on a 
similar but sometimes more elongate and more expanded branch, the peduncle 
purple, with scattered slender paleae and a denser apical cluster, mostly 1.5 to 2 
em, long; disk of receptacle mostly 2 to 8 mm. across, mostly green or brownish, 
covered with short crowded tubercles, the center flattened-hemispherical, 
normally 4-lobed, the lobes short but distinct, extending obliquely outward, the 
margin crenate; involucre broad, white to purple, entire or nearly so; pseudo- 
perianth white to purple, mostly 10 to 12-cleft, the divisions lanceolate, coherent 
at the apex; capsule reddish brown, circumscissile above the middle by an 
irregular line; spores purplish black, becoming semiopaque, 110 to 120 » in 
diameter, with paler, translucent, wavy, and minutely crenulate wings 10 to 12 
wide along the edges, the entire surface (inclusive of the wings) covered over 
by a fine and very irregular reticulum, the meshes mostly 2 to 8 w in diameter, 
inclosed by low and more deeply pigmented ridges 2 to 8 uw high, the periphery 
of the faces appearing irregularly roughened in profile view; elaters (especially 
the spirais) pigmented with purple and sometimes deeply so, variously curved, 
mostly 220 to 240 win length and 14 to 16 uw in diameter, tapering slightly toward 
the ends, sometimes unispiral throughout but usually bispiral in the median 
portion for a variable distance and unispiral at the ends, the spirals sometimes 
difficult to observe in deeply pigmented elaters. 
