Arthur and Kern : North American Peridermium 129 
The deduction was soon made that Cronartium Coniandrae is the 
probable connection, inasmuch as it is an unassociated form with 
nearly an identical geographical distribution, i. c., northern United 
States and southern Canada from ocean to ocean. The fact that 
it is the only unattached Cronartium now known would be enough 
to strongly suggest the relation, but the complete coincidence of 
range is a prominent factor in support of the theory. A further 
bit of evidence is furnished by the field observations of E. W. D. 
Holway who stated on the packet of his Alberta collection that it 
was undoubtedly associated with a Cronartium on Comandra. 
Collectors in the eastern states, especially, should be on the 
lookout for this interesting species. Although apparently very 
meagerly represented in herbaria from this region it doubtless 
occurs not infrequently, judging from the numerous collections of 
the Cronartium on Comandra. 
14. Peridermium Strobi Kleb. Abh. Nat. Ver. Bremen 10: 153. 
1887 
0. Pycnia scattered, honey-yellow, forming minute bladdery 
swellings ; pycniospores hyaline, ovoid or elliptical, 2-4 fj. across. 
1. Aecia on fusiform swellings of the stem or branches, usually 
scattered and solitary, rounded or somewhat elongate, 1-1.5 by 
2-5 mm., subhemispherical, 1-2 mm. high, rupturing irregularly 
along the sides; aeciospores broadly ellipsoid or obovoid, 18- 
24x22— 27 /j.; wall 1. 5-2. 5 n thick, moderately verrucose with low 
uniform papillae, with a smooth area apparent on some spores at 
the base often extending up one side. 
On Pinus Strobus L. Introduced from Europe, through nurs- 
ery stock, into the northeastern Unitel States and Indiana, Ohio, 
and Ontario, Canada, in 1909 according to Spaulding, Bull.. Bur. 
PI. Ind. no. 206, 1911. 
Type collected in Biirgerpark, Bremen, Germany, on the bark 
of Pinus Strobus. It was first observed in 1886 but the informa- 
tion in the original publication is not definite enough to permit 
the designation of any particular collection as type. 
Distribution : Locally introduced with nursery stock from 
Maryland and Vermont to Illinois and Wisconsin, but believed to 
fiave been destroyed in every case ; common in Europe. 
The rust here described under the name Per. Strobi is the one 
