R. H. Howe: MaAnuaAt oF THE GENUS USNEA 13 
equiform (2~8 mm. long.), aééenate, stipate, rectangularly divergent, 
sometimes dichotomous and spiculose e, Apothecia sessile, lateral, 
terminal or subterminal on secondary branches, ample (max. 
diameter 1.5 cm.), thalline exciple smooth or reticulate, periphery 
and exciple ciliate. Spores 5-9 ux 4-6 p. 
CONTINGENT PHASES: Unobserved, except of reduction. 
SupsTRATA: Coniferous and deciduous trees. 
GEOGRAPHICAL DISTRIBUTION: This plant is best exhibited in 
South America, and in our area in Mexico. Throughout the 
United States it is practically confined to the Austral zone, not 
having been collected north of about the 43d parallel of latitude, 
nor west of Minnesota, Iowa, Louisiana, and Texas, or roughly the 
97th meridian, except in Mexico. 
OpseRVATIONS: The typical fertile plant (Bolivia, Ecuador, 
Brazil, and Somaliland) is the most gross and coarse representative 
of the genus. It has been obtained in fruit only in the southern 
limits of the area under consideration, occurring in a most reduced 
state, except in Mexico and the West Indies. In color it is vires- 
cent, soon turning to brown. 
UsnEA Loncissima Ach. 
Type: Not indicated, but the specimen on which the species 
was based is in the Acharian herbarium, Universitetets Botaniska 
Institution, Helsingfors, fide Prof. Dr. Fred. Elfring i /7z. 
TYPE LOCALITY: ‘ Lusatiae.” | 
ORIGINAL DESCRIPTION: ‘‘Thallo pendulo filiformi scabro 
compresso albissimo simpliciusculo longissimo fibrilloso, fibrillis 
horizontalibus approximatis tortuosis simplicibus cinerascentibus,”’ 
Ach. Lich. Univ. 626. 1810, 
Figures: Ach. Nova Acta Soc. Sci. Upsal.7: pl. 7. f. 5. 
1815 [not 1795 as often cited].- Harris, Bryologist 4: p/. 7. 
19Ol. 
Synonymy: Usnea longissima Ach. Lich. Univ. 626. 1810. 
DiaGnosis : Zhallus pendulous, simple, primary branches cov- 
ered with a white furfuraceous crust (soredia). 
DeEscRIPTION —typical: 7ha//us pendulous, simple, mollitinous, 
subterete or compressed, stramineous to virescent, primary cortex 
albo-furfuraceous (soredia), fibrils glabrous; primary branches 
simple, slender (max. length 3 m.), whtte-sorediate ; secondary 
