476 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
pits to indicate their position. The character of the germination 
has been described by Setchell. Literature: 48, 160, 161. 
Doassansia Cornu. 
Ann. Sci. Nat., Bot., vi, 15 : 285. 1883. 
( Setchellia Magn., Ber. Deut. Bot. Ges.. 13 : 408-472. 1895.) 
(Doassansio 2 )sis Diet., Engl. & Prantl Nat. Pflanzenf., I 1 * *: 21. 1897. p. p.) 
Type : Doassansia Alismatis (Nees) Cornu. 
Host: Alisma Plantago. Eur. 
Sori in various parts of the host, usually in the leaves, rather 
permanently embedded in the tissues ; spore balls conspicuous, per¬ 
manent, consisting of a distinct cortical layer and a central mass 
of fertile cells entirely filling the interior or with innermost spores 
supplanted by parenchymatous cells or hyphal threads; spores hya¬ 
line or yellowish , with smooth usually thin walls, of medium size; 
germination often in situ , by means of a short promycelium which 
gives rise to a terminal group of elongated sporidia and these often 
bearing secondary and even tertiary groups. 
The possession of a distinct cortex of sterile cells is the chief 
characteristic of the genus. These sterile cells are often larger and 
more deeply colored than the spores. Because of the variation in 
the different species in the character of the internal cells, it is pos¬ 
sible to make different generic combinations. It seems better to 
follow the generic and subgeneric groups proposed by Setchell 
rather than those later offered by Dietel, especially as the latter’s 
arrangement shows no superiority. The members of this genus 
are found usually on plants living in moist situations, occurring very 
frequently on the Alismaceae. Saccardo describes 23 species ; 10 
species and 1 variety are from North America. 
Setchell, to whom we are chiefly indebted for our knowledge of 
this genus, has proposed the following subgenera: 
Eudoassansia : Body of the spore balls consisting entirely of 
spores which are readily separated from one another at maturity — 
D. Epilobii , D. ranunculina, D. Sagittariae , D. Alismatis , D. 
opaca. 
Doassansiopsis : Central portion of the spore balls consisting of 
