372 HERRE 



elsewhere, but no doubt occurring at the head of similar deep 

 canons rising from the heavy redwood forests of the Pescadero 

 and other coast streams. 



Neph7'07na lusitamcum Schaerer, Enum. Crit. 323. 1850. 

 Ne^hroinhmi lusitant'cum Nyl. Flora 38. 1870. 



XII. Peltigera Willd. 



Thallus frondose, lobate ; beneath veined, villous or fibrillose. 



Apothecia adnate on tips of the more or less extended and 

 narrowed fertile lobes ; spores elongated, slender, 4- to 8-locu- 

 lar, colorless. 



Common throughout, on earth, moss, rocks, and trunks. 

 Peltigera Willd. Fl. Berol. 47. 1787. 



KEY TO THE SPECIES. 



a. Thallus more or less marginally sorediate i. sczdata^ 37-' 



aa. Thallus never sorediate. 



b. Tips of lobes not tomentose ; thallus thick, rather rigid. 



2. rufescens^ 373* 

 bb. Tips of lobes more or less very minutely tomentose. 



c. Thallus medium to large, thin 3. canina^ 373- 



cc. Very thin and papery, expanded. 



4. canina membranacea^ 374* 



I. PELTIGERA SCUT ATA (Dicks.) Leighton. 



Thallus comparatively thick ; much and irregularl}^ lobed ; 

 lobes undulately crenale, their edges confluently gray soredi- 

 ate ; surface smooth, occasionally sorediate ; the lobes some- 

 times finall}' converted into a powdery sorediate heap, losing 

 all semblance of the original thalline form except marginally ; 

 color greenish ashy or gray, or more seldom reddish brown ; 

 beneath white, with broad, tomentose, anastomosing, brown 

 veins ; these dark brown or blackening centrally and finally 

 coalescing so as to obscure the under surface, which appears 

 only as small white or pale brown spots in the dark area. 

 More or less fibrillose neai the margins. Apothecia dark red- 

 dish brown to black. 



On sandstone, tree trunks, and earth, among moss. 



Common at all altitudes above 300 feet. Reaching its great- 

 est vegetative development on perpendicular mossy sandstone 

 cliffs, wdiere it forms extensive mats, but is usually sterile. 



