of the Genus Doassansia , Coi'nu. 13 
Doassansia sagittaricie, Hening, in Sydow., Myc. March., No. 994. 
1886! 
Briard, in Roumegubre, Fung. Gall. Exs., No. 3642. 
1886 ! 
Doassansia opaca, sp. n. 
In the Botanical Gazette for August, 1883 (Vol. VIII, 
p. 2 76), Farlow mentions that he had found Protomyces 
sagittariae , Fuckel, at Newton, Mass. He has kindly allowed 
me to examine these specimens, which agree with my own 
collected in Eastern Massachusetts and Connecticut. They 
have been carefully compared with authentic specimens of 
Fuckers (Fungi Rhenani, No. 1 549), and found to differ so 
decidedly in habit and structure that it seems necessary to 
consider them as specifically distinct. 
This species also inhabits the leaves of Sagittaria variabilis , 
apparently preferring the form called var. latifolia. It forms 
spots which are at first lemon-yellow, then lead-coloured, and 
finally brown. They are circular in shape and somewhat swollen 
on both surfaces of the leaf, like blisters. The leaf is two to 
three times its normal thickness in the region of a spot. The 
individual sori cannot be distinguished, even on holding the 
leaf up to the light and looking through it. In this, it differs 
from all of the species which are described above. The spots 
never grow very large, seldom being over 1 cm. in diameter, 
and they very rarely coalesce. 
The mycelium is perhaps a little coarser than that of the 
preceding species, but does not differ in any other respect. 
The cross-section through the centre of a spot is very 
characteristic (Fig. 72). The sori are situated just between 
the palisade and spongy layers, and, by forcing them apart, 
cause the distortion of the leaf. This position of the sori is 
very uniform in all the numerous specimens examined from 
the various localities. It differs decidedly from the character- 
istic position of the sori in the other species. 
The sori themselves are large (200 /x to 300 /x by So fj . 
to 100 /x), globular-oblong, or almost cuboidal in shape, and 
