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POPULAR HISTORY OJ? 1 LICHENS. 



aceous, — above greenish or olive-coloured, deeply reticulate- 

 lacunose, usually roughened by pale soredia, — below brown- 

 ish-tomentose, with white gibbi; lacinise broad, elongated/ 

 sinuate-lobate, extremities retuse-truncate ; apothecia nor- 

 mally marginal, rarely superficial. 



A common and handsome species, growing on the rugged 

 bark of old forest-trees, particularly the oak, and also some- 

 times on damp rocks. Corticolous specimens are frequently 

 abundantly fertile ; saxicolous forms are generally dwarfed 

 and sterile. Its thecse are long, narrow, slender, and eight- 

 spored ; the spores are of medium size, ellipsoid, sometimes 

 more oblong, rounded at the ends, bilocular, and pale yellow. 

 The spermogones may be recognized as minute, depressed, 

 brownish punctuations, scattered over the surface, and 

 chiefly towards the periphery, of the thalline lobes. They 

 are globular or nut-shaped, unicellular, easily enucleated 

 from the thallus, and have a scarcely visible ostiole. The 

 sterigmata are simple or branching, and consist of a series 

 of cubical, rounded, short articulations. The spermatia are 

 generated laterally from their supports, or from the upper and 

 outer surface of the constituent cells, so numerously as to 

 give the sterigmata a somewhat bristly appearance ; they are 

 linear, straight, squared at both ends, and very minute. In 



