LECANORA. 



219 



under the lens as small black points seated on the verruco- 

 sities of the thallus, or lodged in the sinuses or chinks which 

 separate these. They are globular or ellipsoid, at first pale, 

 but becoming brownish and sometimes almost black ; they 

 have no free cavity. The sterigmata are straight, very slen- 

 der and crowded: the spermatia acrogenous, linear and 

 curved. This and the preceding species have a wide geo- 

 graphical range, occurring in the Antarctic regions, in South 

 America, and other foreign countries. 



b. Apothecia whitish or flesh-coloured. 



5. Lecanora pallescens (pallesco, to grow pale). Thal- 

 lus whitish or greyish, membranaceous-subcartilaginous, tu- 

 berculose-rugose. Apothecium pale flesh-coloured, white- 

 pruinose ; margin tumid. The thallus is frequently isidioid, 

 especially when saxicoious ; on stones also it is often tartare- 

 ous, white, friable, and mealy : it may be somewhat mem- 

 branaceous, especially on trees, and rimose or areolate-ver- 

 rucose. The apothecium is sometimes concave, flattened or 

 tumid with a thinnish or tumid, inflexed or rugose, margin ; 

 it may become abortive and variolarioid. 



A common species, growing on trees, rocks, and stones in 

 lowland, subalpine, and alpine regions; it is abundant on 

 roadside walls. Its most common variety, var. garella, a 



