244 



POPULAR HISTORY OF LICHENS. 



long, slender, linear, eight-spored ; the spores are of medium 

 size, ellipsoid or fusiform, uniseptate, pale-yellow. In the 

 young state of the spore there are sometimes several septa at 

 irregular intervals, or none are visible, the cell being simple. 



11. Lecidea ferruginea (fermgo, iron-rust). Thallus 

 whitish or greyish, leprose, covered with granules or warts of 

 similar colour; apothecia rusty-red, sessile, flat, marginate, 

 at length convex and immarginate. 



A common corticolous and saxicolous species ; in the 

 neighbourhood of Perth it occurs on the beech and other 

 forest-trees, and on micaceous stones in old roadside walls. 

 In the commonest form the apothecia are largish, with a 

 thick, entire or flexuose margin, sometimes crowned by the 

 thallus. The spores are almost identical with those of Par- 

 melia parietina. The spermogones are not very frequent ; 

 they are isolated or grouped, obtuse, dark reddish-brown 

 tubercles, whose internal tissue is white, and very solid ; 

 their cavity branches into several sinuses. The sterigmata 

 consist of almost solid cellules, and are sometimes ramose ; 

 the spermatia are of great tenuity. 



c. Apothecia yellow. 



12. Lecidea ltjtea {luteus, pale yellow). Thallus greyish r 

 green, leprose ; apothecia yellow, thinly margined, sessile, 

 flat. (E. B. 1263.) 



