1894. ] The Genus Riccia. 277 
2. Thallus glaucous or white, clearly reticulate-papillose. 
Spores brown, 65-80y, reticulate................ R. 
glauca 
Spores unknown: thallus milk white above.... &. albida Sulliv. 
#2. Spores very large (130-170) black, opaque. 
Phallus: very Jatge, 4—7%" wide os 0565s cawd as R. Donnelli Aust. 
6. Thallus scaly underneath, not ciliate. 
?. Scales and usually the thallus purple underneath. 
igo ong simple or forked: spores light brown anastomose-reticu- 
ate R. ni, 
Pecus eek ahi 6 hy eb lee eee . nigrella DC. 
Thallus 1-3 dichotomous; spores nearly black, finely reticulate, 
Ramee Wpeiue 2. 626 os Se R. aggregata Underw. 
#2. Scales usually whitish; thallus green underneath. 
Spores light brown, 84-94; scales reaching beyond the margin. 
R. lamellosa_Raddi. 
Spores dark brown, 64-70; scales not reaching the margin. 
R. minima L. 
c. Thallus ciliate at the margins or apices. 
z. Spores black or nearly so. 
Thallus small; spores (about 85.) reticulate with 10-12 areole 
across the surface R. ciliata Hoffm. 
Thallus larger; spores 92-108“; opaque, scarcely reticulate. 
R. hirta Aust. 
9 eee 9 ee) ea, 6 ee ee 
zz. Spores brown. 
Thallus simple or bifurcately lobed, spores 84-92/- 
é sed R tumida Lindenb. 
Thallus stellate or fan-shaped, forming rosettes. 
Spores 68-73; faintly reticulate with 12-14 areolz across the 
convex surface R. Californica Aust. 
Roby De se ee a Se ea ae ae, 
Spores 85-110, reticulate with 7-8 areolz across the convex — 
surface R. Lese 
uriana Aust. 
Bee AO 8 88 666 ee etre ew ae Ce eee 
The following geographic distribution shows rather the 
Paucity of our information than the real limits of the range 
of most of the species. Six species are known only from 
California, viz.: RR. aggregata, Californica, Cataline, cil- 
ata, glauca and tumida. . 
Donnellii is known only from Florida. 
ey albida is known from Texas and Louisiana; R. #irta 
rom New Jersey and California. 
$s = nigrella is known from California, New York and Penn- 
php R. Hubeneriana from Massachusetts, New Jersey 
kee Ohio; R. Lescuriana from New Jersey, Florida and Illi- 
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