OPEGEAPHA. 



249 



lying in all directions or subparallel, linear, generally simple 

 or confluent, flexuose. Thalamium narrow, uniform ; proper 

 margins thick, elevated, wavy. Thecse eight-spored. Spores 

 very minute, obovate, somewhat pointed at extremities, tri- 

 septate, pale yellow. (E. B. 1753.) 



A common species on the smooth barks of the ash, oak, 

 ivy, hazel, currant and other trees or shrubs in various parts 

 of Britain. In germinating, the germ-filaments generally 

 proceed from the terminal contained cellules of the spore, 

 and thereafter the central ones sometimes send forth similar 

 delicate tubular processes. 



5. Opegrapha vulgata (yulgatus, common). Thallus 

 effuse, cartilaginous-membranaceous, cracked and scaly, 

 greenish- white ; lirellse prominent, sessile, variable in size, — 

 shorter ones roundish or oblong, longer ones slender and 

 linear, simple, wavy and shining or greasy. Thalamium 

 rimseform, uniform ; proper margins thick, very round and 

 inflexed. Spores fusiform, five-septate, pale yellow. (E. B. 

 1811, var. vulgata,) 



Common on the fir, ash, birch, oak, elm, apple, holly and 

 other trees in our woods and on our roadsides. 



