258 HERRE 



white or pale, clothed more or less with simple white fibrils. KOH 

 yellow; medulla not colored yellow by KOH. 

 Apothecia black, usually pruinose; margin entire; spores 



14-5 - 19-5 

 On stones and twigs; abundant along the highest peaks of the 



range and one of the commonest and most widespread of hchens. 



7. PHYSCIA AIPOLIA (Ach.) Nyl. 



Lichen aipolius Ach. Lich. Suec. Prodr. 112. 1798. 

 Physcia aipolia Nyl. Flora, 53* 38. 1870. 

 Physcia aipolia Tuck. Syn. N. Am. Lich. I: 73. 1882. 

 Physcia aipolia Herre, Proc. Wash. Acad. Sci. 7: 363. 1906. 



Thallus orbicular, expanded, appressed; lobes much cleft, sinuous, 

 separate and distinct, or coalescent and imbricate; very thickly 

 sprinkled with small white sub-epidermal spots; surface smooth, 

 without soredia; color white or bluish white; beneath dark or black, 

 usually densely clothed with black hispid fibrils; medulla yellow 

 with KOH. 



Apothecia numerous, usually bluish pruinose; disk brownish 

 black; margin thick, prominent, more or less crenate; spores 



5-10 

 /<. 



15-25 



Common on twigs and trunks throughout our range; particularly 

 well developed on Msculus calif ornicus above 2000 feet. Abundant 

 on rocks along the summit of the range. A very common and wide- 

 spread lichen. 



8. PHYSCIA TRIBACIA (Ach.) Tuck. 



Lecanora trihacia Ach. Lich. Univ. 415. 1810. 

 Physcia trihacia Tuck Lich. Am. Sept. No. 85. 

 Physcia trihacia Tuck. Syn. N. Am. Lich. I: 75. 1882. 

 Physcia trihacia Herre, Proc. Wash. Acad. Sci. 7: 364. 1906. 



Thallus more or less orbicular, usually rather small, much lobed; 

 lobes short, intricately laciniate; their margins upturned, much-dis- 

 sected, granulate, becoming lined with confluent soredia; center of 

 thallus sometimes converted into a granulate or sorediate crust; color 



