426 
J. C. ARTHUR 
man on M. alhida florihunda Robins., between Antigua and Volcan de 
Agua, Feb. i8, 1905, II, 5360, and reported by Kern in Mycologia, /. c. 
35. Ravenelia Mainsiana Arthur & Holway sp. nov. (on Mimosaceae). 
Mimosa alhida H.B.K., Guatemala City, Jan. 3, 1915, ii, III, 13. 
Uredinia amphigenous, scattered, oval, 0.2-0.8 mm. long, early 
naked, pulverulent, cinnamon-brown, ruptured epidermis evident; 
paraphyses intermixed with the spores, clavate or capitate, 7-16 by 
29-45 M» the wall slightly tinted, uniformly thin, 0.5-1 ii, the stipe 
often solid; urediniospores ellipsoid or broadly obovoid, 16-18 by 18- 
23 )u; wall cinnamon-brown, 1.5-2 /x, moderately echinulate, the pores 
rather indistinct, 8-10, scattered. 
Telia amphigenous, scattered or in small groups, round or oval, 
0.4-0.8 mm. across, subepidermal, soon naked, blackish, ruptured 
epidermis conspicuous; teliospore-heads irregular, flat, dark chestnut- 
brown, 3-6 cells across, 55-71 by 74-93 At> each spore bearing 7-9 
spines, up to 3 ^ long; cysts pendent from base of pedicel, swelling and 
bursting in water. 
This rust differs from R. Mimosae-albidae Diet, in well marked 
characters. The teliospore-heads are flat and irregular, not hemi- 
spherical and regular, the urediniospores are somewhat smaller and are 
echinulate not verrucose, while the paraphyses are smaller, lighter- 
colored, and thinner-walled than in the other species. 
The host was determined by Mr. Paul C. Standley of the National 
Herbarium, who also determined the host for R. Mimosae-albidae 
(no. 137). 
The species is named in honor of Dr. E. B. Mains, assistant botanist 
in the Indiana Experiment Station of Purdue University, who de- 
tected the specific distinctions and has drawn up the diagnosis. Dr. 
Mains has also done a large share of the microscopic work on the other 
species of Ravenelia listed in this paper, and also has given much aid 
in the critical study of some of the species of other genera, in all of 
which he has displayed excellent judgment and a fine sense of di- 
agnostic values. 
36. Ravenelia spinulosa Diet. & Holw. (on Caesalpiniaceae). 
Cassia hiflora L., Solola, Jan. 27, 1915, II, iii, 134; San Lucas 
ToHman, Dept. Solola, Feb. 3, 1915, II, III, 182; Guatemala 
City, Feb. 14, 1917, II, iii, 86y. 
Cassia sp., San Rafael, Dept. Guatemala, Jan. 9, 1915, II, III, 
44] El Rancho, Dept. Jalapa, Feb. 13, 1915, II, HI, 20Q. 
The paraphyses of this species are quite variable; often there are 
