92 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
0.3 to 0.8 mm. in diameter, sessile, black or brownish black, flat or slightly convex, the 
exciple of the same color and often disappearing; hypothecium colorless’ or slightly 
brownish (in ours dark brown); hymenium pale; paraphyses commonly simple with 
apices sometimes thickened and darker-colored; asci cylindrico-clavate; spores 4 to 
8-celled, acicular or oblong-cylindrical, usually straight, 18 to 32 ” long and 2.5 to 4 4 
wide. 
In ours the apothecia are often clustered and usually strongly convex, the exciple 
commonly absent. 
Collected at Tofte and not previously reported from Minnesota. On poplar bark. 
Found elsewhere on the island of Cuba. 
BUELLIA De Not. Giorn. Bot. Ital. 2!: 195. 1846. 
The thallus is crustose and variously granulose, verrucose, and areolate, rather more 
inclined to areolate conditions than are the similar thalli of Lecideas and seldom show- 
ing typically granulose conditions. Though the thallus is on the whole rather more 
conspicuous than in the genus just named, its minute anatomy commonly reveals the 
same rudimentary condition, the cellular cortex being absent or barely suggested in 
the sections. Neither can algal and medullary layers be distinguished. The thallus 
lies mainly above the substratum, to which it is attached by hyphal rhizoids. It is 
seldom of any considerable thickness, yet it is by no means so frequently evanescent 
as is the rather more rudimentary thallus of the Lecideas and some other closely 
related genera. The algal symbiont is a Cystococcus-like plant. 
The apothecia are small or more rarely middle-sized, are circular or irregular in out- 
line, and in position relative to the thallus vary from sessile to immersed conditions. 
The disk is commonly black and is flat or convex. The proper exciple is also commonly 
black macroscopically, but more usually dark brown in section, as is also the hypothe- 
cium. The exciple is very similar to that of the Lecideas, and species of the two genera 
appear so much alike externally that their separation in the field can be accomplished 
only after long acquaintance. The hymenium is commonly pale or pale brownish. 
The spores, as the genus is here limited, are typically brown and 2-celled (4-celled ina 
few forms admitted and indicated in the descriptions), and vary in form from oblong 
to ellipsoid. Decolorate conditions of spores are occasionally met with in the genus. 
As to structure of the thallus and apothecia (exclusive of the spores) the genus 
seems nearest to Lecidea and Rhizocarpon, while the spore characters seem to indicate 
a relationship with such genera as Rinodina and Physcia. And while the relation- 
ship with Lecidea is on the whole much closer than that with Rinodina, the spores 
always serve to distinguish between the present genus and the Lecideas, while in spite 
of the usual presence of a well-defined thalloid exciple in Rinodina, it is by no means 
always easy to distinguish between Buellias and Rinodinas. 
Some fourteen forms occur in the State. On trees, rocks, and old wood. 
Type species Buellia canescens (Ach.) De Not. op. cit. 197. 
KEY TO THE SPECIES. 
Parasitic on other lichens, and no thallus discernible. 
Exciple commonly disappearing; apothecia minute, black. 9. B. parmeliarum. 
Exciple persistent or tardily disappearing. 
Spores normal. 
Spores 9 to 13 » long and 3 to 6 # wide......-.-.- 7. B. saxatilis. 
Spores 10 to 18 » long and 6 to 8 » wide......... 8. B. inquilina. 
Spores 4-celled. 
Spores 10 to 16 « long and 8 to 6 » wide......... 10. B. parasitica. 
Spores 21 to 28 » long and 7 to 9 » wide........- 11. B. glaucomaria, 
