146 



PLATE 15. fig. 7. 

 Hazslinszkya demissa (Tuck.) 

 Paraphyses with spore-sac and spores. 



2. Opegrapha Humb. Fl. Friberg, 57. 1793- 



The thallus is rudimentary and for the most part hypophloeodal, 

 finally forming a thin film over the substratum. Structurally it is 

 almost as simple as in Hazslinszkya, consisting of a much branched 

 network of slender hyphae in which the chains of algae ( Chroolefus 

 umbrina) are suspended. Numerous haustorial branches enclose the 

 algal cells ; endotrophic haustoria also occur. 



The apothecia are usually numerous, small, linear, more or 

 less curved, projecting somewhat above the surface of the sub- 

 stratum. The hypothecium (perithecium) and epithecium are black. 

 The paraphyses are usually branched, granular and more or less 

 gelatinized. 



The spores are colorless, spindle-shaped to almost acicular, usually 

 four-celled. 



The Opegraphae range from the south to the north temperate 

 zones. The majority of the American species occur in the East. 

 They live principally upon trees, rarely upon rock, and are some- 

 times parasitic upon other lichens. 



PLATE 28. 

 Opegrapha vaiua Pers. 



1. Plant natural size. 



2. A small portion magnified. 



2'. Vertical (transverse) section through apothecium, thallus and sub- 

 substratum (semidiagramatic) . 



3. Section of apothecium. 



4. Section of thallus. 



5. Paraphyses and spore-sac. 



6. Spores. 



7. Algae and hyphae. 



3. Graphis Ach. Lich. Univ. 46. 1810. 



The species of Graphis in so far as they occur in the territory 



are simple in structure, and in all but spore-characters they closely 



resemble the Opegraphas. The thallus is partly hypophloeodal 



finally forming a thin film over the substratum. The algae (Chroo- 



