152 ARTHUR: NEW SPECIES OF UREDINEAE 
This is a common and conspicuous species in the Rocky 
Mountains, and extends sparingly eastward across the plains and 
over the Allegheny Mountains. For a long time it has been con- 
sidered heteroecious and probably the early stage of the common 
Uromyces on Astragalus. Both its distribution and morphological 
characters favored this view, and many attempts at cultures were 
undertaken to substantiate the assumed connection but without 
success. Observations in the field have yielded no strong evidence 
that the aecia were followed by telia on Astragalus, but rather 
that they were not. At various times it has been suggested that 
the telial form on the same hosts as the aecia, Uromyces Tranz- 
schelii, an apparently short-cycle species having pycnia associated 
with the telia, might be derived at times from the aecia, and all 
be one autoecious species. If this were true, we should have the 
anomalous condition of a short-cycle and a long-cycle form asso- 
ciated at times so intimately that only culture demonstration 
could separate them. In the meantime while actual experimental 
knowledge is awaited, it seems best to designate the aecia by a 
name that will distinguish them from other aecia on similar hosts. 
Some of the collections above cited are said to be on Euphorbia 
montana, which may be true, although the preponderance of 
probability points to E. robusta, a far more common species in the 
region covered, and under this name they have been listed. 
Aecidium Mozinnae sp. nov. 
O. Pycnia chiefly epiphyllous, few in orbicular groups, honey- 
yellow, inconspicuous, subepidermal, globoid, 90-125 across; 
ostiolar filaments present, abundant. 
I. Aecia hypophyllous, encircling the pycnial area, on yellowish 
spots 2-5 mm. across; peridium cylindric, the margin erect and 
erose; peridial cells quadrate or rectangular, 19-24 by 29-34 b, 
abutted or slightly overlapping, the outer wall 10-12 u thick, 
transversely striate, smooth, the inner wall 3-5 4 thick, strongly 
verrucose; aeciospores angularly ellipsoid or globoid, 19-23 by 
24-29 u; wall nearly or quite colorless, 22.5 » thick, closely and 
noticeably verrucose. 
On Mozinna spathulata (Miill.-Arg.) Ortega (Jatropha spathu- 
lata Miill.-Arg.), State of Guanajuato, Mexico, July 11, 1899, 
J. N. Rose & Walter Hough 8999. 
