300 



POPULAR HISTORY OP LICHENS. 



spored; its spores resemble those of some Graphideae and 

 Urceolarias. The enclosed cellules in this and other cellu- 

 lar or mini form spores, are regarded by some authors as nu- 

 cleiform hollows or cavities in a solid spore, which are occu- 

 pied by a transparent, oily or granular protoplasm. The 

 apothecia, on superficial examination, may be confounded 

 with those of the genus Urceolaria. 



2. Thelotrema exanthematicum. Thallus leprose, grey- 

 ish or ochry ; external exciple immersed by its base in the 

 rock, plano-convex, protuberant, at first closed, becoming 

 centrally radiate-fissured, and at length open, — internal ex- 

 ciple waxy, with a connivent margin, enclosing a yellow, 

 discoid thalamium. Spores linear-oblong or lanceolate, ta- 

 pering at ends, three-septate, pale yellow ; their surface 

 roughened by fine, distant points. (E. B. 1184.) 



On calcareous rocks in lowland and subalpine districts, 

 but rare ; a very pretty but minute species. The apothecia 

 bear some resemblance to those of the genus Gyalecta. 



Nat. Ord. XV. VERB U CAMACE2E, Fries, 

 Fam. Char. Thallus cmstaceous. Ajpothecium rounded, fre- 



