CLINTON: NORTH AMERICAN USTILAGINEAE. 
437 
out at the circumference about 1 /x so that the enveloping membrane 
is rather closely applied chiefly 17-22 /x, rarely 25 /x, in length. 
Host: fiporobolus asperifolius, Ariz., Colo., Mont., Nev., N. Mex., 
Ore., Rocky Mts. (type), Wash., Wyo. 
The large thick walled sterile cells are quite striking in appear¬ 
ance and are one of the chief characters that distinguish this species 
from both Tilletia fusca and Tilletia montana. The germination 
of the spores is not known. 
* * * Spores verruculose. 
Tilletia Maclagani (Berk.) Clint. 
Ustilago Maclagani Berk., Grev., 3 : 58-59. 1874. 
Ustilago rotundata Arth., Bull. Ia. Agr. Coll., 1884: 173. 1884. 
Tilletia rotundata Ell. & Ev., 1 N. A. Fungi, 1894. 1887. 
Tilletia rotundata Mass., 1 2 Kew Bull., 153 : 145. 1899. 
Tilletia Maclagani Clint., Journ. Myc., 8 : 148. 1902. 
Exsiccati : Ustilago rotundata Artli., on Panicum virgatum, Ell. & Ev., 
N. A. Fungi, 1894. 
Sori in ovaries and occasionally in anthers, inconspicuous, con¬ 
cealed by the enveloping glumes, upon rupture shedding out a dusty 
red brown spore mass; spores showing different stages of develop¬ 
ment, the older light to dark reddish brown, chiefly subspherical or 
spherical though occasionally more elongated or somewhat irregular, 
with a thick wall (3-4 /x) closely covered with verruculations, 18-27 
/x in length. 
Host: Panicum virgatum , Conn., Ia. (type U. rotundata ), 
Ivans., Neb.; Montreal (type). 
The writer is indebted to Massee for part of Berkeley’s type 
specimen of Ustilago Maclagani in the Kew herbarium. This 
proves to be the same as Arthur’s Ustilago rotundata as has been 
suggested in Farlow and Seymour’s Host index. Some writers in 
this country have considered this species as identical with Tilletia 
pulcherrima , also occurring on Panicum virgatum. The two 
1 Ellis and Everhart call the fungus Ustilago rotundata Arth., but say that 
it is evidently a Tilletia and so American botanists have since called the 
fungus Tilletia rotundata (Arth.) Ell. & Ev. 
2 Massee gives his name for the authority of this combination. 
