ARTHUR: NEW SPECIES OF UREDINEAE 151 
Aecidium Tithymali sp. nov. 
O. Pycnia hypophyllous, scattered sparsely over the surface 
of the leaf, preceding and accompanying the aecia, punctiform, 
honey-yellow or brownish, noticeable, subepidermal, globoid or 
flask-shaped, 110-150 broad; ostiolar filaments 60-100 u long. 
I. Aecia hypophyllous, evenly and loosely scattered, at first 
bullate and opening by a pore or irregular break of the epidermis; 
peridia erect or recurved, torn, fragile; peridial cells rhomboidal, 
10-15 by 23-274, somewhat overlapping, the outer wall 5-74 
thick, striate, the inner wall 2-3, thick, verrucose; aeciospores 
globoid or broadly ellipsoid, 18-22 by 19-24 u; wall nearly or quite 
colorless, thin, I-1.5 , finely verrucose. 
On Tithymalus commutata (Engelm.) Kl. & Garcke (Euphorbia 
commutata Engelm.), Decorah, Iowa, June, 1883, E. W. D. Hol- 
way; same, June 20, 1885, E. W. D. Holway (Barth. N. Am. Ured. 
703); Beloit, Wisconsin, May 30, 1910, J. J. Davis; Lafayette, 
Indiana, June 7, 1901, H. B. Dorner (type); same, May 13, 1910, 
Kern & Billings; Plummer Island, Maryland, May 30, 1903, 
P. L. Ricker 1055; Crawfordsville, Indiana, May 17, 1913, F. D. 
Kern. 
On Tithymalus leiococcus (Engelm.) Small (Euphorbia texana 
Boiss.), San Antonio, Texas, March 16, 1900, Wm. Trelease; 
same, February 16, 1914, Arthur & Fromme 5300. 
On Tithymalus missouriensis (Norton) Small (Euphorbia 
dictyosperma Auct.), Lincoln, Nebraska, April 28, 1902, Geo. G. 
Hedgcock. 
On Tithymalus robusta (Engelm.) Small (Euphorbia robusta 
Small), Colorado, July, 1888, C. H. Demetrio (Ellis & Ev. N. Am. 
Fungi 2215); Flagstaff, Arizona, June, 1891, D. T. MacDougal; - 
Larimer County, Colorado, July 2, 1894, C. F. Baker 261; Colorado 
Springs, Colorado, August 2, 1900, E£. T. Harper 368; Wasatch 
County, Utah, August 3, 1905, A. O. Garrett (Fungi Utah. 96); 
La Veta, Colorado, 2,100 m. alt., June 21, 1907, F. E. & E. S. 
Clements (Crypt. Form. Colo., 594); Boulder, Colorado, May 
13, 1910, E. Bethel; same, August 23, 1911, Bethel, Arthur & 
Kern 509; Denver, Colorado, May 24 and June 2, 1915, E. 
Bethel; Ft. Collins, Colorado, May 23, 1916, J. C. Arthur; Golden, 
Colorado, May 27, 1916, J. C. Arthur; Rimrock Station, Montana, 
August 2, 1917, E. Bartholomew 6213. 
