484 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
* * * PSEUDODOASSANSIA. 
Doassansia obscura Setcb. 
Doassansia obscura Setch., Proc. Amer. Acad. Arts Sci., 26: 16. 1891. 
Sori not evident, the spore balls being produced in the interior of 
the basal parts of the petioles without special distortion or discolora¬ 
tion though evident upon rupture of the enclosing tissues ; spore 
balls arranged in single rows in the air chambers, consisting of a dis¬ 
tinct cortex surrounding several irregular layers of spores and a cen- 
tial mass of indefinite fungous hyphae, oblong to subspherical, large, 
150-300 p in length ; cortical cells rather light brown and thin 
walled, ovoid to obovate or subcordate, conspicuous, 12-18 /x x 8- 
l-/x; spores light brown, chiefly subspherical, with thin, smooth 
walls, about 8—12 p in diameter. 
Host: Sagittaria variabilis, Conn, (type), Mass. (type). 
The central mass of fungous filaments in the spore balls distin¬ 
guishes this from any of the other species of Doassansia. For this 
reason Setchell placed it in a distinct subsection. The heart shaped 
cortical cells are also peculiar. Sometimes Doassansia deformans 
forms groups of spore balls in the petioles and is likely to be mis¬ 
taken for this species. The former can be told usually by its smaller 
darker colored spore balls. Unless the petioles are torn open for 
examination Doassansia obscura is so inconspicuous that it will 
readily escape detection ; this may possibly account for the lim¬ 
ited distribution accorded the species. Its germination has been 
described by Setchell. Literature: 160,161. 
Tracy a Syd. 
Hedw., Beibl., 40 : (3). 1901. 
(Cornuella Setch., Proc. Amer. Acad. Arts Sci., 26: 19. 1891.) 
Type : Tracya Lemnae (Setch.) Syd. 
Host: Spirodela polyrrhiza. Mass. 
Sori in the leaves (fronds), permanently imbedded in the tissues ; 
spo't e balls conspicuous, without cortical layer , composed of a single 
layer of fertile cellsenclosing a network of septate filaments / spores 
