IOWA ACADEMY OP SCIENCE 
75 
Aecia subepidermal, ampliiginous, irregularly scattered over more or less 
rounded yellowish discolored areas which measure about 5 mm. across, short 
cylindric or deeply cuplike, 0.4-0. 7 mm. across; peridium ample, of irregularly 
polyhedral cells about 15x20 micra, minutely granular; seciospores globose, 
often more or less angular, 12-18x10-15 micra; wall very light yellow, about 1.5 
micra thick, smooth.* 
Collected but once and then not in abundance. The discolored areas are of 
sufficient size and of deep enough a color to render the secia quite conspicuous. 
No trace of pycnia were observed in the material examined. Probably has its 
alternate form on some grass or sedge. 
240. Aecidium Compositaeum Mart. 
On Polymnia canadensis L., and Rudheckia laciniata L. 
A superficial comparison of the aecia on these two hosts is sufficient to con- 
vince one that they belong to two species of rusts. On Polymnia the infected 
area is rather large, bright yellow, and has the cups scattered irregularly and 
unevenly over the under surface. On Rudheckia the discoloration is pale, tend- 
ing to brownish in the center, the cups being grouped closely on the underside 
and pale yellow. The collection on Polymnia is interesting as the only previous 
record for this host is Racine, Wis. The material was found on the windward 
side of a hill, with no apparent source of infection at hand. The aecia on Rud- 
beckia were rather eommon and fairly abundant. 
241. Aecidium Hydkophylli Peck. 
On Nemopliylla microcalyx (Nutt.) Pisch & Mey. (Macrocalyx Nyctelea 
Kuntze.) 
Rather abundant in one station, but no clue to its relationship was found. 
242. Aecidium hydnoideum B. & C. 
On Dirca palustris L. 
A very conspicuous form, but not common or abundant. 
243. Aecidium Polemonii Peck. 
On Polemonium reptans L. 
Rather abundant in one station. Probably connected with TJromyces acumi- 
natus Arth. on Spartina. 
244. Aecidium Xauthoxuli Peck. 
On Xanthoxylon americanum Mill. 
An inconspicuous form which was found sparingly on wind swept hillsides 
in late July. 
OEDER EXOBASIDIALES. 
Family Exol)asidiaceae. 
245. Miceosteoma Juglandis Sacc. 
On Juglans cinerea L. 
Not uncommon, causing white areas on the under surface of the leaf. 
*Aecis subepidermalis, ampliiginis, irregularis disperis, brevis cylindraceis, vel 
cupuliformibus, °.4-0.7 mm. crassis ; peridiis amplis, cellulis irregularibus polygoniis, 
granularibus ; sporis globosis, vel angulariis, 12-18x10-15 micra; membranis flavidis 
vel subhyalinibus, circa 1.5 micra crassis. 
