2l6 



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

 erally present in the exciple ; the thecium consists of two 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. 



