26 RICCIACEAE 
PLATE 00. RICCIA AMERICANA. 
. Dry plant, natural size. 
Plants from material preserved in alcohol, natural size. 
Thallus-segment, alcoholic material, Х 5 
Thallus-segment, from dry specimen, X то 
Фо Nw 
5. А thick free-hand transverse section from near apex of thallus, showing por- 
tions of the scales, 23. 
6. Outline of transverse section from same segment as no. 5 but farther back, 
2. 
-9. Outlines of microtome cross-sections of thallus segment ; по. 7, near apex, 
no. 8, well forward, по. 9, toward base, X 12. 
10 and тт. Outlines of cross-sections of thallus-segment from another plant, 12. 
12. Antheridium, showing non-elevated ostiole, 12. 
13. Epidermis near thallus-apex, Х 225. 
14 and 15. Epidermis from older parts, 225. 
16. Ventral scale, X 2 
17. Portion of thin transverse microtome section of thallus, ЖЕ: 
18. Outer face of spore, ` 305. 
19. Inner faces of spore, Х 305. 
20. Outline of optical section of spore-wall, showing its relative thickness, 305. 
Figs, 1, 4-6, and 18-20, drawn from specimen collected in Fruit Vale, Alameda 
County, May 2, 1895; 2, 10, 11, and 13-16, San Francisco, April, 11, 1896 ; 3, 7-9, 
12, and 17, Fruit Vale, February 1, 1896. 
7. Riccia Campbelliana sp. nov. 
sulcus acute, often obscure toward basal parts, the margins, Ой | 
drying usually ascending, erect, ог inflexed-connivent ; terminal | 
lobes oblong or obovate, obtuse, less commonly subacute ; 
, 
verse sections, including margins, 2-5 (mostly 2%) times broader 
than high, thickness of thallus 25-35 cells in median parts, air- 3 
canals narrow ; cells, often enlarged, densely filled with a finely | 
the thallus ; epidermis primarily unistratose, the cells large, ob- | 
long-elliptical in vertical section or subquadrate-elliptical, mostly | 
higher than broad (40-75 и x 25-50 М), long intact, disintegrated | 
in the older parts and replaced 
subjacent lay 
