ARTHUR: New specites oF UREDINEAE 579 
recurved, erose, peridial cells strongly imbricated, rhomboidal be- 
low, becoming ovate-lanceolate above when seen in radial section, 
outer wall nearly or quite smooth, inner wall somewhat thicker, 
closely and prominently verrucose with slender, elongated warts; 
aeciospores angularly and broadly ellipsoid or nearly globoid, 18- 
21 by 24-209y; wall pale yellow, rather thick, 2-2.5u, greatly 
thickened above, 7—9u, closely and finely verrucose. 
On Macrosiphonia brachysiphon (Torr.) A. Gray, Guayamoba 
‘Canyon, Sierra Madre Mts., Chihuahua, Mex., Sept. 27, 1903, 
M. E. Jones 7774. The strongly thickened apical wall of the 
spores readily distinguishes this form from similar forms on the 
Apocynaceae, and especially from those mentioned below. 
Aecidium obesum sp. nov. 
O. Pycnia amphigenous, numerous, crowded in opposed 
groups, 0.3-I mm. across, small, inconspicuous, punctiform, honey- 
yellow becoming brownish, flattened-globoid, 96-1284 broad by 
58-77u high; ostiolar filaments 30-48y long 
I. Aecia hypophyllous, gregarious in circular groups 2-7 mm. 
across, crowded on scarcely thickened but much discolored spots, 
exserted portion evanescent; peridial cells imbricated, easily falling 
apart, obovate-lanceolate in radial section, inner wall finely verru- 
cose, outer wall somewhat thicker, strongly verrucose, aeciospores 
globoid or somewhat ellipsoid, large, 28-35 by 32-40; wall color- 
less, greatly thickened, 5—8,, irregular within, forming an angular 
or stellate cavity, closely and prominently verrucose. 
On Apocynum hypericifolium Ait. (A. cannabinum hyperici- 
folium A. Gray), Manhattan, Kanas, May 15, 1886, W. A. Keller- 
man (type), (Ellis, N. Amer. Fungi 1823; Vestergren, Micr. Rar. 
Sel. rror); Merriam, Neb., July 11, 1899, J. M. Bates. This 
form has been confused with Aecidium Apocyni Schw., which 
occurs east of the Alleghany mountains from New Jersey to 
North Carolina. The eastern form has a firm peridium, and small 
aeciospores, 16-20u in diameter, with thin walls, I-1.5y. 
Through the kindness of Prof. T. J. Burrill I have been able to 
examine the collection recorded in Burrill’s Parasitic Fungi, page 
236, which was made by Mr. A. B. Seymour at Normal, IIL, 
June 14, 1882, and find that it consists of a single leaf of Apocynum 
hypericifolium with a single group of pycnia, but gathered too 
early to show even the beginning of aecia. It is impossible to 
decide even approximately upon the identity of the fungus. 
