302 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
ing differences in the male branches. In A. lateralis these seem to be in- 
variably short, extending but slightly beyond the margin of the thallus and 
not broadening out to any marked extent. Upon these branches the antheridia 
form a small group in a rather vaguely defined median area and show very few 
marginal paleae or none at all. In A, elegans the male branches vary greatly 
in size, some of them being 1 em. long or more and correspondingly wide, and 
the numerous antheridia are situated on a clearly defined and slightly raised 
receptacle, surrounded by a fringe of paleae.. The differences in the female 
branches, although less constant, are sometimes striking. In A. lateralis these 
are usually almost as short as the male branches, although they broaden out a 
little more; in A. elegans they vary in length to the same extent as the male 
branches. In exceptional cases, unfortunately, a female branch in A. lateralis 
may be somewhat elongated, so that this distinction must be used with caution. 
13. Asterella reticulata Evans, sp. noy, 
Thallus green above, usually more or less pigmented with purple on the 
ventral surface and along the margin, sometimes with scattered dots or splotches 
on the upper surface, mostly 1 to 8 em. long and 2.5 to 5 mm. wide, plane or 
slightly concave with undulate, scarcely crispate, margins, often scarious when 
old and somewhat incurved when dry; branching (so far as observed) ventral, 
sometimes lateral, sometimes by means of apical innovations, in the latter case 
occasionally soon repeated, thus giving rise to a jointed appearance, the keel 
broad and rounded ; epidermis composed of cells with somewhat thickened walls 
but without distinct trigones, averaging about 50 X 25 w; pores distinetly 
elevated, measuring (with their surrounding cells) mostly 110 to 140 w in 
length and 80 to 120 » in width, surrounded by 6 to 8 radiating series of cells 
with 3 or 4 cells in each series, the radial walls slightly thickened; cells contain- 
ing oil bodies, green tissue, and compact tissue all as in A. elegans ; mycorhiza 
often abundant; ventral scales much as in A. elegans, the appendages usually 
borne singly but sometimes in pairs, narrowly subulate or lanceolate, mostly 
0.75 to 0.9 mm, long and 0.12 to 0.15 mm. wide, the margin sometimes bearing 
® spinelike tooth near the base, the apex acuminate; cells as in A, elegans; 
inflorescence doubtful but probably autoicous; male inflorescence (only 2 cases 
observed) as in A. elegans, terminal on a more or less elongated branch; female 
inflorescence borne on a more or less elongated branch; peduncle pigmented 
with purple (except in the apical portion), bearing scattered lanceolate paleae 
with a denser tuft at the apex, mostly 1 to 1.5 em. high; disk of receptacle 
purple (so far as observed), mostly 2.5 to 3 mm. across, covered with coarse but 
low tubercles, hemispherical in the center, normally 4-lobed, the lobes short but 
distinct, extending obliquely downward and outward, the margins and in- 
volucre as in A. elegans; pseudoperianth brownish, not pigmented with purple, 
mostly 8 to 10-cleft with lanceolate divisions coherent at the apex; capsule 
brown, circumscissile above the middle by an irregular line, the operculum com- 
ing off in one piece; spores rather dark brown, mostly 70 to 80 » in diameter, 
with a wavy wing 8 or 4 uw wide and often 4 to 8 » thick around the spherical 
face and much broader but otherwise similar wings along the other edges, 
the whole surface (except sometimes close to the wings) covered over with 
an irregular and fairly coarse reticulum, with meshes mostly 8 to 12 » wide, 
inclosed by a system of narrow and thick ridges, these mostly 3 to 4 » wide 
and equally thick, the broad edges of both wings and ridges marked by darker 
irregular lines and occasional lighter interstices, the surface otherwise smooth 
or vaguely and minutely punctulate; elaters pale brown, variously curved, 
mostly 200 to 250 » long and 12 to 14 » wide, tapering slightly toward the blunt 
