Riccia 17 
measuring the diameter of the convex face. Its large spores (90— 
105 /”), the broad divergent thallus-lobes and other minor charac- 
ters stand in the way of its reference to R. glauca. 
2. КІССІА TRICHOCARPA M. A. Howe, Bull. Torr. Bot. Club, 25! 
joe 184. pl. 337. 1898. 
Thallus in rosettes about 2 cm. in diameter or forming some- 
what irregularly radiating masses; the principal divisions linear, 
2-6 times dichotomous, .75-1.5 (mostly 1) mm. in width, often 
black below and at margins, densely clothed at the sides with white 
or tawny setae .3—65 mm. long, those toward the apices often in 
as many as 8—12 irregular series, mostly distinct at insertion, with 
sharp, rigid, rarely slightly uncinate points, the terminal thallus- 
lobes obcuneate or oblong-elliptical, obtuse or subacute, nar- 
rowly and rather deeply unicanaliculate toward the apices or sub- 
bicanaliculate, the furrow at the extremities commonly concealed 
by the trichomes, the median sulcus sometimes nearly vanishing . 
toward the base, margins obtusely rounded, tumid, often connivent 
on drying, the furrow then thatched by the somewhat forwardly 
directed setae ; dorsal surface light green, minutely and regularly 
reticulate; ventral surface nearly plane and flat, with a few very 
inconspicuous scales on either side of the median lineat the apices, 
falsely squamose in the basal parts through delamination due to 
marcescence ; width of transverse sections 1.6—3 times their height, 
the posterior subquadrangular with a light median sulcus, the 
margins becoming more tumid and rounded in proceeding toward 
the apex and the sulcus now and then double, the sections convex 
ventrally only in the extreme apical region ; 20—28 cells in thick- 
ness in median parts, texture nearly solid, the air-chambers narrow 
‚апа vertical ; epidermis primarily bistratose, the superficial layer at 
first papillate, afterwards collapsed, and in the older parts reduced 
to a flattened cellulose membrane incumbent on the lower layer : 
monoicous : antheridia scattered, the ostioles elevated about . 1 mm.: 
sporogonia numerous, in a single or double series, immersed, 
finally—especially when dry—hemispherical-protuberant above, 
together with the long-unruptured covering, or subconical, the cov- 
ering marked with a dark-purple spot and bearing with rare excep- 
tions 1-12 setae ; spores soon black and very opaque, narrowly 
or not at all margined, 90–120/ in maximum diameter, minutely 
granulose-papillate, with 0—12 areolae (visible only in the younger 
spores) across the convex face, the walls of these with irregularly 
thickened and salient angles, thus often giving this face in profile 
the appearance of bearing columnar or wart-like elevations, areolae 
across one of the plane faces 5-7 in number, scarcely elevated at 
the angles, 
