GENERA AND SPECIES. 191 



7. Psoroma. 



Thallus foliose, branching, lying flat over substra- 

 tum. The alga3 are Protococcus. It is perhaps prob- 

 able that this genus is phylogenetically derived from 

 Pannaria which genus it resembles in all but the algal 

 characters. 



Apothecia discoid, margin irregular. Disk reddish- 

 brown. Spores colorless, simple, spindle-shaped. 



1. Psoroma hypnorum. Thallus consisting of as- 

 cending scales which are more or less lobed, reddish- 

 brown. Apothecia medium to large, margin crenulate 

 and bearing thalloid outgrowths. Disk reddish-brown. 

 Spores typical, 13.5/x X 9/w- 



2. Psoroma stellata. Thallus of imbricate, many 

 cleft, ascending lobes with crenate margin, pale brown 

 above ; whitish beneath with numerous rhizoids. Apo- 

 thecia few, small to medium, sessile. Disk convex, 

 pale brown to reddish-brown. Spores rare, not seen. 



8. Pannaria. 



Thallus foliose, lobed and usually of a reddish-brown 

 color above, pale beneath. The lower forms, however, 

 approach the crustose type. The alga? are blue-green 

 in color, and occur in groups (^Poly coccus punctiformis). 

 The apothecia are usually quite small, discoid, sessile. 

 Disk flattened, with margin somewhat raised, reddish- 

 brown ; hypothecium colorless. The spores resemble 

 those of the preceding genus. 



The genus is somewhat southern in its range ; the 

 species occur upon moss, soil, rock and trees. At present 



