THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 105 



Apothecia small, .5 to .75 mm. wide; disk black, papillate, with a 

 thin grayish, at first slightly elevated, margin, continuing plane with 

 the finally convex disk, but not wholly excluded; epithecium brown 

 black, gradually paling downward, with KOH pale violaceous; hypo- 

 thecium pale brown and darkening; hymenium pallid, with I turning 

 intensely blue; paraphyses conglutinated; asci saccate; spores color- 



io - 16 



less, munform, - //. 



24 - 36 ^ 



On rocks in the mountains; New Almaden, 1200 feet; Castle Rock, 

 3000 feet; and on maritime rocks near Pescadero. A lichen of 

 northern, alpine, and southern Europe. 



2. RHIZOCARPON VIRIDI-ATRUM (Flk.) Korb. 



Lecidea mridi-atrum Floerke, 



Rhizocarpon mridi-atrum Korber, Syst. Lich. Germ. 262. 1855. 



Diplotomma mridi-atrum Jatta, Syll. Lich. Ital. 432. 1900. 



Thallus greenish or sulfur-yellow, of minute, thickish, tartareous, 

 flat or rounded granules or squamules; the hypothallus but little, or 

 not at all evident; KOH - ; CaCl 2 O 2 - ; medulla not affected by I. 



Apothecia numerous, of medium size, innate or closely appressed, 

 dull black, not pruinose; the disk more or less minutely roughened, 

 at first plane, with a thin, entire or irregular margin; soon moderately 

 convex and the margin disappearing; paraphyses indistinct, coherent; 

 epithecium broad, black, purplish red with KOH; hypothecium 

 blackish-brown; thecium deep blue with I; spores quadrilocular, ellip- 

 soid or oblong, dark brown, becoming nearly black, - /*; 



perhaps murilocular, but too dark to determine positively. 



A distinct species, very rare with us; collected but once, on sand- 

 stone in the foothills 4 miles west of Stanford University, at an alti- 

 tude of 400 or 500 feet. Not rare in Europe, but apparently not dis- 

 tinguished by American collectors. 



3. RHIZOCARPON GEOGRAPHICUM (L.) DC. 



Lichen geographicus Linne, Spec. Plant. 1140. 1753. 

 Rhizocarpon geographicum DC. Fl. Fr. 2: 365. 1805. 

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



