THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 153 



On dolomite at New Almaden, at an altitude of about 1200 feet. 

 Rare and inconspicuous with us, but widely distributed in Europe 

 and North America and often common on calcareous rocks. 



2. PLACYNTHIUM DUBIUM Herre, new species. 



Thallus of very small or minute, expanded or sub-erect squam- 

 ules, fringed with short finger-like lobules, or with irregularly cut 

 margin; squamules often crowded into a rough crust, or again 

 sparsely distributed, sub-orbiculate or effuse; color a very dark 

 brown, seldom paler; black beneath; on a blue-black hypothallus. 



Apothecia minute, superficial, sessile, constricted at the base, the 

 disk very slightly convex, blackish red-brown; the thin, entire mar- 

 gin of the same color as the thallus; paraphyses free, from simple 

 finally somewhat branched, at first thread-like, becoming rather 

 broad, septate, with enlarged, very pale brownish tips; hypothecium 

 colorless or very pale yellow; thecium very deep blue with I; spores 

 variously shaped, slender spindle-shaped to broadly ellipsoid, often 

 with one end drawn out to a long tip, from simple with broken con- 

 tents, and bilocular, to 4-locular, the septa faint, 



igi - 244 



On sandstone and among mosses on sandstone, in the foothills 

 near Stanford University, at an altitude of 150 feet. Exceedingly 

 rare in fruit. 



XXXVII. Pannaria Del. 



Pannaria Delise, in Duby Bot. Gallic. 606. 1830. 



Thallus granulose, squamulose, to minutely foliaceous, upper 

 surface more or less isidiose, or naked ; usually with a well developed 

 black or blue-black hypothallus; rarely with rhizoids; alga Nostoc; 

 only the upper side with a cortex. 



Apothecia at first innate, at last sessile and dish- or shield-shaped, 

 lecanorine ; margin of a pseudoparenchyma cortex and a medullary 

 layer enclosing algae; hypothecium colorless; spores colorless, sim- 

 ple, ellipsoid to spindle-shaped. 



A large genus of about 50 species, often difficult to determine, 

 dwelling on a variety of substrata. 



