84 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
ening, the disk flat or slightly convex, the exciple of about thesa me color or becoming 
darker, usually persistent; hypothecium colorless to brownish; hymenium of same 
colors and frequently darker below; paraphyses commonly simple, sometimes slightly 
thickened and brownish toward the apex; asci clavate; spores ovoid to ellipsoid, 7 
to 12 » long and 3 to 5.5 » wide. 
A single collection was made at Tower. On Peltigera canina. 
Known elsewhere in North America in Massachusetts, Illinois, and Newfoundland. 
Found also in Europe, Asia, and Africa. 
Biatora heervi of the preliminary reports. 
4. Biatorina prasina (I’r.) Fink. 
Micarea prasina Fr. Syst. Orb. Veg. 257. 1825. 
Thallus composed of very minute granules, these closely clustered or even some- 
times heaped more or less and forming a widely spread, frequently subleprose, usually 
dark olivaceous-green or blackish crust; apothecia small or minute, 0.2 to 0.5 mm. in 
diameter, commonly convex or globular and the exciple disappearing early, brown 
or in ours more commonly black or blackish, the whole structure in ours frequently 
irregular or depressed; hypothecium pale or brownish; hymenium pale below and 
commonly darker above; paraphyses commonly simple, somewhat gelutinized and 
indistinct; asci clavate; spores commonly 2-celled, but in ours more commonly 
simple, oblong-ovoid, 8 to 12 » long and 3.5 to 5 » wide. 
Dr. A. Zahlbruckner has placed ours under subspecies byssacea (Zwackh) Th. Fr., 
based on the darker color of the apothecia, the darker apices of the paraphyses, and 
the frequently simple spores. 
A single collection was made at Bemidji. On old wood. 
Reported elsewhere in North America from Massachusetts, Illinois, Georgia, Wash- 
ington, and California. Known also in Europe. 
Biatora prasina of the preliminary reports. 
BILIMBIA De Not. Giorn. Bot. Ital. 2': 190. 1846. 
The thallus is crustose and commonly composed of minute granules, which run 
together into a smooth or variously leprose or verrucose crust, never distinctly areolate, 
in any of our species at least, though squamose in some North American species. 
Thallus on the whole somewhat less conspicuous and also more rudimentary internally 
than in Lecidea, though seldom disappearing entirely. In position relative to the 
substratum and mode of attachment to it similar to Lecidea. The algal symbiont is a 
modified form of Cystococcus, in which the cells are perhaps on the whole smaller. 
than usual and united in larger numbers. 
The apothecia, like those of Biatorella and Biatorina, are small or minute, none of 
our members of this or of those genera reaching the middle-sized conditions so frequent 
among Lecideasand Bacidias. In form of apothecia, nature and constancy of exciple, 
color of hypothecium and hymenium, and appearance of paraphyses and asci, the 
present genus is essentially like the four closely related genera just mentioned. How- 
ever, the spores differ from those of Biatorinas in that they are from 4 to 9-celled, and 
from those of Bacidias in that they are distinctly wider and on the whole shorter and 
fusiform or finger-shaped instead of being needle-shaped. 
The Bilimbias are evidently most closely related to the Bacidias, and indeed it may 
well be doubted whether the species should be separated into two genera. The 
species, however, form two groups, whether genera or not, and though the student 
will find some trouble at first in deciding with which a species having a given spore 
form should be piaced, the difficulty will pass away with a little observation of the 
various forms. Transitional spore forms scarcely exist in our species, though some 
real difficulty due to such is encountered in the study of certain forms from other 
regions. The plant of the preliminary reports placed in the genus Lecidea, under 
the name Lecidea acclinis Flot., appears to present stronger affinities with the present 
genus and has been transferred. 
