Arthur and Kern : North American Peridermium 125 
seum which we have seen, bears the additional data, Santa Rita 
Mts., July 13, 1881, Pringle no. 32). 
Distribution : The Rocky mountains from their eastern limits 
in Colorado to the eastern slopes of the Coast Range, and north 
and south from the Canadian to the Mexican boundaries. The 
telial stage on Castilleja is now known from nearly the same range. 
This rust, as here represented, consists of two forms some- 
what unlike in gross characters and hosts, but agreeing well in 
microscopical characters and apparently in telial relations. The 
form listed above on Pinus ponder osa is the one on which Peck’s 
name flamentosum was based. This form is especially charac- 
terized by elongated cylindrical sori and by the presence of longi- 
tudinal filaments within the peridium. The specimens on Pinus 
scopulorum, a close ally of P. ponderosa, while not possessed of 
the typical characters in so striking a manner as the original seem 
to belong here. The fact that none of these specimens seem typ- 
ical may be due to their state of preservation, all of them being 
considerably weathered, whereas the original specimen on P. 
ponderosa was collected and preserved in prime condition. It was 
with one of these semi-typical forms that Hedgcock reports suc- 
cessful cultures on Castilleja. 
The form on Pinus contorta and its two close allies agrees in 
making noticeable swellings of the branches and in microscopical 
characters but it differs in having shorter, more nearly hemispher- 
ical sori, which are sometimes irregular in outline. It is with 
material of this sort that Meinecke reports cultures on Castilleja. 
The apparent difference between this Peridermium and the one 
used by Hedgcock in his cultures on Castilleja has led the latter 
to assume (Phytopath. 2: 176-7) that two entirely independent 
species exist. Our examination of a number of specimens of 
Cronartium on Castilleja in both uredinial and telial stages from 
all parts of the geographical range has failed to indicate any 
morphological variations and this has led us to the opinion that 
we may. possibly be dealing with two Peridermium races, with 
certain structural differences, which have the same telial connec- 
tion. We have, therefore, ventured to place the Pinus contorta 
forms, to which the name Per. stalactiforme belongs, under Per. 
filamentosum although it is done with some doubt. Further cul- 
