334 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Uleiella (Ulea), Ustilaginoidea, Ustilagopsis. All of the 24 genera, 
except five (Kuntzeomyces, Melanotaenium, Polysaccopsis, Schinzia, 
Schroteria), are found in North America. Saccardo, including 
volume 16, Syll. Fung., has described about 568 species, but a num¬ 
ber of these are now known not to be distinct. There are 205 species 
(with varieties) described here from North America. These have 
been reported on 442 hosts, distributed under 164 host genera and 
35 families of flowering plants. 
Artificial Key to Genera. 
The following key to the genera reported in North America is 
based on their more evident morphological characters. 
i. Spores single. 
A. Usually forming a dusty sorus at maturity (see also i. B. 2, 
hi. A. la). 
1. Large, usually 16-35 /x. 
a. With an elongated hyaline appendage . JVeovossia 
b. Without a conspicuous appendage . . Tilletia 
2. Small to medium, usually 5-18 /x. 
a. Sorus covered with a false membrane of fungous cells 
Sphcicelotheca 
b. Protecting membrane, if any, of plant tissue Ustilago 
B. More or less firmly agglutinated at maturity (see also hi. B. 1). 
1. Firmly agglutinated into irregular tubercular nodules 
Melanopsichium 
2. Developed around a central columella (rarely becoming 
dusty) ...... 
C. Imbedded in leaves at maturity. 
1. Usually hyaline or light colored 
ii. Spores chiefly in pairs. 
A. Forming an agglutinated sorus (on leaves) 
B. Forming a dusty sorus (inside peduncles) . 
hi. Spores in more or less regular balls. 
A. Forming a dusty or granular sorus at maturity. 
1. Spore balls consisting only of fertile cells. 
a. Usually evanescent, olive or black brown 
Cintractia 
Entyloma 
Schizonella 
Myko syrinx 
Sorosporium 
