136 



8. BUELLIOPSIS. 



I have separated this genus from Bit-cilia, from which it is distin- 

 guished by the dark four-celled spores. It also differs somewhat in 

 its apothecial characters. In Buellio^psis the apothecia are discoid, 

 the margin is slightly elevated and somewhat irregular or wavy in 

 outline. Only a few species have come to my notice. The thallus 

 is crustaceous and comparatively rudimentary, consisting of a defi- 

 cient network of hyphae with a few algae ( Cystococcus) , and does not 

 enclose the apothecia as much as in BitelUa ; its color is grey to 

 greenish. Further careful study of the genus is necessary in order 

 to determine its limitations and position in the family. 



In the early part of their development the spores are not con- 

 stricted at the septa, but at maturity they become considerably con- 

 stricted, much as in Bucllia ; they are rarely three-celled. 



PLATE 15. fig. 5. 



BUELLIOPSIS VERNICOMA (Tuck.) 

 Paraphyses and spore-sac with spores. 



9. BUELLIA De Not. Giorn. Bot. It. 2: 195. 1851. 



In fiueZh'a+the apothecia are more or less immersed in the thallus 

 which is thickly crustaceous and usually distinctly areolate ; the 

 spores are distinctly two-celled, dark, usually constricted in the mid- 

 dle. Reinke considers this genus closely related to Rinodina, which 

 is true when superficially considered. In both genera the thallus is 

 crustaceous and the apothecia are more or less immersed ; the 

 apothecia are also more or less irregular in outline, especially in 

 Buellia, which also has a dark hypothecium, and the thecium is 

 also frequently quite dark in color. 



The thallus varies from grey, through greenish to more or less 

 dark. (JSuellia will be further considered under Rinodina.} 



Most of the species occur upon rocks, more rarely upon bark 

 and old fences. 



PLATE 20. 



BUELLIA PARASEMA (Ach.) Fr. 



1 . Plants natural size. 



2. Plants magnified. 



3. Section of apolhecium. 



