112 GUIDE TO THE STUDY OF LlCHENS. 



rather small, somewhat immersed, flattened. Disk 

 dark. Spores simple, colorless, elliptical. 



7. 



Another insignificant group having a close resem- 

 blance to Bilimbia and by some authors placed with 

 Biatora. It differs from Bilimhia in that the hypo- 

 thecium is dark. The genus requires further careful 

 study. Only a few species are reported. These occur 

 upon tree-trunks and moss. 



1. Celidiopsis platycarpa. Thallus rudimentary, 

 granular, gray to greenish. Apothecia small, ele- 

 vated margin. Disk flattened, black. Spores color- 

 less, rather variable in size and form, four-celled, 

 22/x X V 



8. Buelliopsis. 



This genus is represented by a few species. It dif- 

 fers from Buellia in its spore-characters, otherwise it 

 is the same. The spores are four-celled, dark, con- 

 stricted at the transverse septa. 



1. Buelliopsis vernicoma. Thallus granular, spread- 

 ing, gray to greenish. Apothecia small, elevated mar- 

 gin. Disk flattened, black. Spores dark-brown, dis- 

 tinctly four-celled, usually constricted at the septa, 

 16/x X 6.5/x. 



9. Buellia. 



The Buellias are well characterized, and are repre- 

 sented by a large number of species. The general char- 

 acters of the thallus resemble those of Biatora and 

 Lecidea. The apothecia are medium in size and are 



