260 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
his thanks to the various curators who have made this possible. In 
citing specimens under the individual species the following abbrevi- 
ations are used: N. Y., for the herbarium of the New York Botanical 
Garden; H., for the herbarium of Harvard University; U. S., for the 
United States National Herbarium; C., for the herbarium of the 
Canadian Geological Survey; C. C. H., for the herbarium of Miss 
Caroline C. Haynes; and Y., for the herbarium of Yale University. 
Duplicate types of the new species proposed have been deposited 
in the United States National Herbarium. 
KEY TO THE SPECIES, 
a, Dichotomous branching the usual type, ventral branching rare or lacking__ b. 
a, Dichotomous branching rare or lacking, ventral branching the usual type; 
dorsal air chambers subdivided by numerous supplementary partitions, 
the epidermal pores apparently fewer than the chambers_____________ j. 
bv. Dorsal air chambers not subdivided by supplementary partitions; epidermal 
pores clearly as numerous as the dorsal chambers___________---_-___. Cc. 
db. Dorsal air chambers more or less subdivided by supplementary partitions; 
epidermal pores apparently fewer than the chambers____.--_.-_-___ jf. 
ec. Cells with oil bodies present in the epidermis; cells immediately surrounding 
the epidermal pores with thin radial walls; inflorescence paroicous; seg- 
ments of pseudoperianth becoming free with age; spores yellow, coarsely 
reticulate (at least on the spherical face)_-----.--.___-________ d. 
ce. Cells with oil bodies lacking in the epidermis; cells immediately surrounding 
the epidermal pores with thickened radial walls; segments of pseudo- 
perianth not becoming free with age; spores dark brown to nearly black, 
not coarsely reticulate_________--_-_----_-_- eee é. 
d, Female receptacle distinctly lobed, smooth or nearly so; spores mostly 80 to 
904 in diameter, the surface with fine lines in addition to the coarse 
reticulum________-_--_-- 1. A. tenella (p. 261). 
d. Female receptacle scarcely lobed, covered with low and coarse tubercles; 
spores mostly 60 to 65 w in diameter, the surface punctulate, 
2. A. ludwigii (p. 266). 
e. Inflorescence autoicous; female receptacle hemispherical, with low and 
coarse tubercles and short but distinct lobes; pseudoperianths extending 
obliquely outward___--__-__--_--___-_-- 3. A. pringlei (p. 271). 
e. Inflorescence paroicous; female receptacle bluntly conical, smooth or nearly 
so, scarcely lobed; pseudoperianths extending almost vertically down- 
ward______ - -- - -. 4 A. palmeri (p. 273). 
jf. Xerophytic in habit, the margins of the thallus strongly incurved when 
dry----~--------- +--+ - g. 
jf. Not xerophytic in habit, the margins of the thallus scarcely or not at all 
incurved when dry_-- --- -- - wenn eee h. 
g. Appendages of the ventral scales 1 or 2, forming a conspicuous white clus- 
ter at the tip of the thallus; inflorescence monoicous; spores with wings 
and a fine surface reticulum, but without coarse ridges on the faces. 
5. A. saccata (p. 276). 
y. Appendages of the ventral scales (mostly) 2 to 4, not forming a conspicu- 
ous white cluster at the tip of the thallus; inflorescence dioicous; spores 
with coarse ridges on the faces, in addition to the wings and the fine 
surface reticulum__________-___-__ 6. A. californica (p. 280). 
