URCEOLARIA. 



231 



areolate; hypothallus black. Apothecia at first seated in 

 thalline areolae, patellate and scutellate, black, naked, or 

 greyish-pruinose. There are many varieties in which the 

 apothecia are isolated or crowded, irregular in form, with a 

 thick, flexuose, or unequal margin. 



Not uncommon on rocks and stones of various kinds in 

 lowland and subalpine districts ; it is frequently the cause 

 of the grey colour or crust of rocks and cliffs. Its spores, 

 in the specimens we have examined, resemble those of Phy- 

 scia ciliaris or Parmelia stellaris, but are smaller than either. 



2. Urceolaria scruposa (scruposuSy rugged). Thallus 

 tartareous-farinose, whitish, greyish, or lead-coloured, areo- 

 late-verrucose or granulose, sometimes dissolving into a 

 pulverulent mass ; hypothallus white. Apothecia immersed, 

 — younger concave, margin contracted or connivent, rugose ; 

 older flattened, patellate or scutellate, black, greyish-pruinose, 

 the margin sometimes obsolete. (E. B. 1732, var. vulgaris; 

 266, var. bryopliyta ; 1954, var. diacapsis.) 



A comparatively frequent species in lowland and subal- 

 pine districts, incrusting rocks, stones, dead wood, tree- 

 trunks, the ground or moss. Saxicolous forms are some- 

 times isidioid ; muscicolous varieties, like similar forms of 

 Lecanora pallescens and tartar ea, differ most from the others 



