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[Vol. 8, 
cycle of both genera, afford reasons for excluding the Urticastrum rust 
from these genera. This rust is to be distinguished from species of Uredo- 
peltis and Phakopsora by the colorless walls of the teliospores and by their 
germination without a resting period. Melampsoropsis, Chrysomyxa, 
and Cerotelium are genera in which the teliospores germinate without a 
resting period and are arranged in closely compacted chains. There is no 
characteristic of the telium which would necessarily prevent this rust from 
belonging to any of the last mentioned genera, except perhaps that there 
are a smaller number of teliospores in a chain in the Urticastrum rust than 
are usually found in the rusts of these genera. 
The uredinium of the Urticastrum rust, however (fig. 6), is bordered 
by a few colorless, incurved paraphyses, and the walls of the echinulate 
urediniospores are colorless and the spores are borne in a manner similar 
to that in Aplopsora Nyssae. It therefore differs in these respects from spe- 
cies of Melampsoropsis (Chrysomyxa of some authors) which have catenu- 
late, verrucose urediniospores, usually with a surrounding peridium. Chry- 
somyxa as used by Arthur lacks uredinia and in consequence will be dis- 
FiG. 6. Section through uredinium of Cerotelium Dicentrae showing peripheral paraphyses 
and manner in which urediniospores are borne. 
regarded. This species might be placed in the genus Cerotelium as originally 
described by Arthur^ (p. 30), except for the presence of paraphyses in the 
uredinium instead of a peridium. As a result of the study of additional 
material Arthur^ (pp. 505-507) brought together in each of the genera 
Phakopsora, Cerotelium, and Cronartium species with a peridium, species 
with paraphyses united below into a pseudoperidium, species with hyphoid 
or incurved paraphyses, and species with neither peridium nor paraphyses. 
In the first two genera, species can be found showing gradations, such as 
incurved colorless paraphyses, colored thick-walled paraphyses, paraphyses 
united to a greater or less extent to form a pseudoperidium, paraphyses 
accompanying a peridium, and a peridium only. In consequence the 
^ Arthur, J. C. New species of .Uredineae. Bull. Torrey Bot. Club 33: 27-34. 1906. 
8 Arthur, J. C. Relationship of the genus Kuehneola. Bull. Torrey Bot. Club 44: 
501-511. 1917. 
