Io6 HERRE 



Thallus greenish yellow to bright lemon-yellow, determinate, 

 rimose areolate, the flat areolae crowded into a chinky crust, or else 

 the areolae are scattered and tumid, forming small clumps; hypothal- 

 lus distinct, black; medullary hyphae blue with I; not affected by 

 other reagents. 



Apothecia immersed or between the areolae and on the same level 



as the thallus, mostly angular from pressure of adjoining areolae or 



other apothecia, small, numerous and often grouped; disk always 



flat, black, opaque, the margin thin, black, indistinct; epithecium 



brownish-black; paraphyses loosely coherent, the brown tips scarcely 



thickened ; hypothecium brownish black; thecium colorless, blue with 



16 — 20 



I; spores dark brown, 2 to 4 locular and muriform, -^ > fi- 



20—40 



The forms contigua and lecanorina of authors are not rarely found 

 mixed with the type, on the same specimen. 



A beautiful and conspicuous lichen. Abundant on various rocks 

 at 2500 feet and above, and in the cold and foggy San Francisco 

 region descending as low as 500 feet. Found in nearly all moun- 

 tainous regions of the world and characteristic of all very high peaks. 



4. RHIZOCARPON BOLANDERI (Tuck.) Herre. 



Buellia holanderi Tuck. Gen. Lich. 189. 1872. 



Buellia holanderi Tuck. Syn. N. Am. Lich. II: 103. 1888. 



Thallus indeterminate and spreading extensively, cartilaginous, 

 of small to very small, brown or reddish-black, sometimes shiny, flat 

 or slightly concave, round or sinuate squamules; these with a shghtly 

 elevated black border, scattered or approximate; in the latter case 

 forming an areolate-diffract crust upon a conspicuous black hypo- 

 thallus that to the naked eye gives the predominant color to the thal- 

 lus; no chemical reactions of thallus or medulla. 



Apothecia small, dispersed, from partially innate to sessile; disk 

 flat or shghtly convex, naked, black; margin quite thin, becoming 

 finally obscure; epithecium dark brownish violaceous black; thecium 

 pale, deep blue with I; paraphyses conglutinate; hypothecium of 

 same color as epithecium; asci saccate and inflated saccate, about as 

 high as thecium ; spores colorless to dark smoky gray and dark brown, 

 solitary or in twos, with a thick gelatinous halo, muriform, oblong 



