Arthur and Kern: North American Peridermium 117 
Scotch pine has been reported from North America, and as this 
one was found where telia of the species had been collected. Two 
other scanty collections were made in the vicinity both on pine 
seedlings, thought to be Pinus Banksiana, which resemble the 
Peridermium on Pinus sylvestris, but they are not included for 
want of sufficient collateral evidence. The history of this dis- 
covery is related by Dr. Davis in a recent number of Phytopath- 
ology (3: 306. Dec., 1913). 
4. Peridermium montanum Arth. & Kern, Bull. Torrey Club 
33: 413- !9 o 6 
0. Pycnia 0.3-0.5 mm. broad by 0.5-1 mm. long, low-ccnoidal, 
55-65 n high. 
1. Aecia flattened laterally, 1-1.5 mm. long by 0.5-1 mm. high; 
peridial cells ovoid to ellipsoid in face view, 23-35 *45-65 n, often 
acutish at one or both ends, slightly overlapping and easily sepa- 
rating, the side walls 3-4 /u. thick, the inner wall rather finely ver- 
rucose with low papillae of irregular outline ; aeciospores oblong 
to linear-oblong, 16-24x32-45 /x, the wall 2-3 /x, closely and 
rather coarsely verrucose. 
On Pinus Murrayana Oreg. Com., Montana ( Blankinship , 
Stuart ) ; Washington ( Suksdorf 302 & 645) ; Alberta ( Holway ) ; 
Rocky Mountains, Canada? (Macoun). 
On Pinus scopulorum (Engelm.) Lemm., Montana (Kelsey). 
Type collected at Rimini, Montana, on Pinus scopulorum, June 
24, 1889, F. D. Kelsey. 
Distribution : The far northwest, from central Montana west- 
ward and northward. 
The standing of this species remains unchanged, since its publi- 
cation. One or two observers have reported finding Coleosporium 
Solidaginis in close proximity to it and have suggested a possible 
relation but since the specimens referred here differ very mate- 
rially in microscopic characters from Per. acicolum of the east- 
ern states, which is now known to belong to Coleosporium Solida- 
ginis, the species is still maintained. A more likely connection 
would be with Coleosporium arnicale, which may possibly occur 
on more than one species of Arnica from the region indicated 
above. 
