EVANS—THE NORTH AMERICAN SPECIES OF ASTERELLA. 289 
always entire, that the disk of the female receptacle is flat or nearly so, and that 
the spores lack a coarse reticulum on the spherical face, Among Mexican 
species A. pringlei bears a certain resemblance to A. venosa, in spite of its more 
xerophytie tendencies; but its undivided dorsal chambers, its smaller epider- 
mal pores, the large and toothed appendages of its ventral scales, its 
autoicous inflorescence, its 12 to 16-cleft pseudoperianth, and its darker, almost 
opaque spores are distinctive characteristics, 
9. Asterella rugosa Evans, sp. nov. 
Thallus sometimes green throughout but usually with some purple pigmenta- 
tion, especially along the margin and on the ventral surface, mostly 1.5 to 2 
cm. long and 8 to 10 mm. wide, plane above or with a shallow median groove, 
the margins mostly crenate and closely undulate-crispate, not incurved when 
dry, branching normally by forking but sometimes by apical innovations or lat- 
eral intercalary outgrowths, the keel narrow but rounded; epidermis composed 
of cells with thin walls and small but very distinct trigones, averaging about 
80 X 25 uw; pores slightly elevated, measuring (with their surrounding cells) 
mostly 80 to 110 » in length and 60 to 90 uw in width, surrounded by 6 (some- 
times 5 or 7) radiating series of cells with 3 or 4 cells in each series, the radial 
walls more or less thickened and showing distinct trigones; cells containing 
oil bodies not abundant, much as in A. tenella; green tissue loose, the air 
chambers in 8 or 4 layers, those of the dorsal layer sparingly subdivided by 
supplementary partitions extending to the epidermis; compact tissue occupying 
about one-half the thickness of the thallus in the median portion, thinning out 
gradually on the sides and extending about one-fourth the distance to the 
margin, composed of cells with thin unpitted walls; mycorhiza present; ventral 
scales small, narrowly to broadly ovate, usually purple throughout or with the 
tips of the appendages hyaline, the marginal slime papillae more or less persist- 
ent but inconspicuous; cells containing oil bodies mostly 15 to 20, scattered ; ap- 
pendages mestly borne singly but sometimes in pairs, not constricted at the 
base and not distinctly marked off from the basal portion, subulate from a 
broad base, mostly 0.45 to 0.6 mm. long and 0.15 to 0.2 mm, wide at the base, 
usually entire but sometimes with 1 or 2 coarse and irregular teeth, acuminate, 
the cells averaging 50 X 20 u»; inflorescence dioicous (apparently); male 
inflorescence borne on a leading branch and not limiting its growth, consisting 
of a narrow elongated median group of antheridia without marginal paleae; 
ostioles long; female inflorescence borne on a similar branch; peduncle with a 
loose apical cluster of slender paleae, otherwise naked or nearly so, not pig- 
mented, about 1 cm. long; disk of receptacle 3 to 4 mm. across, the upper sur- 
face slightly convex, covered with low and coarse tubercles, rugose when dry, 
searcely or not at all lobed; involucre narrow, its features not clearly made 
out; pseudoperianths normally 4, extending almost vertically downward, white 
or brownish, mostly 12 to 14-cleft, the divisions lanceolate and coherent at the 
apex; capsule brown, its method of dehiscence not observed; spores brown, 
mostly 80 to 90 w in diameter, with pale yellowish brown, wavy and vaguely 
crenulate wings 8 to 10 » wide along the edges, the wings marked by narrow and 
low irregular and darker ridges, extending outward but growing narrower and 
paler toward the wing margins, the spherical face covered over with a fine and 
irregular reticulum, with meshes about 10 » in diameter, inclosed by a system of 
anastomosing ridges similar to those on the wings, the plane faces with similar 
but lower and often indistinct ridges, sometimes almost smooth, coarser folds 
or ridges not present; elaters brown, more or less curved, mostly 140 to 200 uw 
1103892—20 4 
