338 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
Arthur’s specimens of Ustilago minima were also provided with such 
a membrane though apparently because of the maturity of the speci¬ 
mens it did not show so prominently. In his brief description of 
the species Professor Arthur does not mention this character. Both 
specimens also seem to differ from specimens of Ustilago hypodytes, 
even on the same host, by somewhat smaller and more regular 
spores. The author has collected the true Ustilago hypodytes on 
Stipa spartea in Illinois, and Ellis reports it (Bull. Torr. Bot. Club, 
24 : 457; ibid ., 27 : 62) on Oryzopsis cuspidata from Colorado. 
An examination of the latter specimen in the 1ST. Y. botanical garden 
shows it to be as reported. Thus these two plants are hosts for 
both species. The sterile threads of the false membrane of 
U. minima are elongated, apparently usually simple and with 
indistinct lumen. With age they perhaps gelatinize so that the 
false membrane partially disappears. It is possible that this mem¬ 
brane is formed as a protection to the sorus only when this is not 
closely enveloped by the leaf sheaths; if this is the case then it 
scarcely constitutes a distinct specific character. 
Ustilago hypodytes (Schl.) Fr. 
Caeoma hypodytes Schl., FI. Ber., 2 : 129. 1824. 
Ustilago hypodytes Fr., Syst. Myc., 3 : 518. 1829. 
Erysibe hypodytes Wallr., FI. Crypt. Germ., 2 : 216. 1833. 
Uredo hypodytes Desire, Ann. Sci. Nat., ii, 13 : 182. 1840. 
Ustilago Lygei Rab., [Unio. Itin. Crypt., 4. 1866.] ? 
Ustilago hypodytes var. Lygei Rab., Fungi Eur., 1800. 1873. 
Ustilago Sporoboli Ell. & Ev., Bull. Torr. Bot. Club, 24 : 282. 1897. 
Ustilago funalis Ell. & Ev., Bull. Torr. Bot. Club, 24 : 457. 1897. 
Sorosporium Williamsii Griff., Bull. Torr. Bot. Club, 29 : 296. 1902. 
Exsiccati : Sorosporium Williamsii Griff., on Stipa Richardsonii, Griff., 
West. Amer. Fungi, 306; Ustilago hypodytes (Schl.) Fr., on Agropyron 
occidental , Griff., West Amer. Fungi, 234; on Distichlis spicata, Griff., 
West Amer. Fungi, 235 ; on Elymus condensatus, Griff., West Amer. Fungi, 
233 ; on Elymus striatus , Griff., West Amer. Fungi, 201 ; on Stipa buco- 
tricha , Ell., Ev., & Barth., Fungi Col., 1899 ; on Stipa occidentalism Griff., 
West Amer. Fungi, 236 ; on Stipa spartea , Griff., West Amer. Fungi, 3, 
Seym. & Earle, Econ. Fungi, Clinton Ust. Supp. C, 71; Ustilago minima 
Arth., on Stipa eminens, Ell. & Ev., N. A. Fungi, 3135, Ell. & Ev., Fungi 
Col., 537, Syd., Ust., 210. 
Sori surrounding internodes (beginning at their base) for usually 
the greater part of their length, linear, hidden by enveloping leaf 
