2l6 



structure they closely resemble those of Stictina ; the algae are gen- 

 erally present in the exciple ; the thecium consists of t\vo layers ; 

 the upper layer is formed by a network of hyphae which extend for 

 the most part vertically and contains a quantity of air ; the lower 

 layer consists of agglutinate hyphae which extend horizontally. 

 Sometimes the hypothecium is more or less cortical in structure, es- 

 pecially near the periphery. 



The spores are mostly spindle-shaped to acicular, colorless, two- 

 to four-celled and, as in Stictina, present degenerative characters. 



The Stictas are much less southern in their range than the Stic- 

 tinas. The majority occur in the temperate zones ; some are dis- 

 tinctly northern. They grow upon rocks, moss and trees, to which 

 they are loosely attached. 



PLATE 76. 

 STICTA AMPLISSIMA (Scop.) Mass 



1. Small thallus, natural size. 



2. Section of apothecium. 



3. Section of thallus. 



4. Paraphyses and spore-sac. 



5. Spores. 



6. Algae. 



