110 
Mycologia 
Colorado, P. Engelmanni , was erroneously included among west- 
ern forms, probably because published as on Pinus Engelmanni, 
now referred to the genus Picea. 
The five recognized species in 1896 had expanded to fifteen 
species when the present authors published in 1906, seven being 
on leaves and eight on bark. At the present time all the seven 
leaf forms seem to be worthy of recognition, one additional species 
has been described by Long in the meantime, one species has been 
introduced from Europe, and two forms are to be separated in 
this paper, making eleven leaf forms altogether. The greatest 
upheaval and readjustment has taken place among the bark forms. 
Much reliance was necessarily placed at first on the form of the 
gall, but later information derived in part from cultures has 
given better apprehension of the species. The aecial form of the 
oak Cronartinm , P . cerebrum, is now made to include the western 
form, P. Harknessii, as well as the three supposed new species of 
our former paper, P. fusiforme, P. globosum, and P. mexicanum. 
The two diverse-appearing forms, P. filamentosum and P. stalac- 
tiforme, have been united with some hesitation. The misuse of 
the name, P. pyriforme, has been rectified, and the aecial form of 
the currant rust, P. Strobi, which has been introduced from 
Europe since our former paper, has been added. Altogether five 
species of bark forms are recognized, the same as previously, but 
differently assorted. 
So far as known, fourteen species out of the sixteen included 
in this paper are native to North America, and of the fourteen 
only two are also known outside of North America. One of 
these, P. Rostrupi, is common in Europe, and the other, P . cere- 
brum, is common in Japan. 
The remaining two species have been introduced from Europe 
in recent years, and neither of them is yet established. One of 
them, P. Strobi, is of such economic interest that a stubborn fight 
is being waged against it in this country. The other one, P. 
Fischeri, is only known in one tree nursery in Wisconsin, and 
was first seen in 1912. It was found on Pinus sylvestris, being 
the first collection of a P eridermium on the leaves of this conifer 
to be found in North America. In the North American Flora 
(vol. 7, page 94) P. oblongisporium, which also occurs on Pinus 
