1918] JACKSON—PUCCINIA 303 
The species as here considered follows closely the original interpretation of 
ArTuuR. It should be noted that certain collections (Holway 3450, 3668) 
show only the thick-walled form, and the sori are chiefly epiphyllous, while 
in the typical form the sori are chiefly hypophyllous. The two Pringle col- 
lections add new hosts for the species. The first mentioned was obtained 
through the courtesy of Hotway, the other from a phanerogamic specimen 
in the herbaria of the New York Botanical Garden and of the Field Museum 
(sheets 104882, 2620977). 
16. Puccinia rata Jackson and Holway, sp. nov. 
O and I. Pycnia and aecia unknown. 
II. Uredinia amphigenous, chiefly hypophyllous, scattered, 
round, standing out from surface of leaf, small, o. 2-0.4 mm. across, 
early naked, becoming pulverulent, cinnamon brown, epidermis not 
conspicuous; surrounded by abundant encircling paraphyses, 
standing well out from substratum, paraphyses incurved, clavate, 
15-18 by 1oo~125 4, wall colorless or very slightly tinted with 
brown, uniform, thin, o.5-1 4; urediniospores globoid or broadly 
obovate, 24-29 by 26-32 uw; wall dark cinnamon brown, 2.5-3.5 # 
thick, rather closely echinulate; pores 4-5, scattered. 
III. Telia hypophyllous, scattered or gregarious, round, small, 
©.2-0.4 mm. across, early naked, becoming pulverulent, early 
formed sori surrounded by paraphyses like the uredinia, later formed 
sori without paraphyses; 'teliospores broadly ellipsoid, 26-30 by 
32-42 pw, rounded at both ends, slightly or not constricted at septum; 
wall uniform, chestnut brown, 3.5—5 u thick; thickened to 5-7 » at 
apex and over pore of lower cell, which is usually placed half way 
from pedicel to septum, prominently and evenly tuberculate with 
closely set low tubercles, 1 u in height, having polygonal bases; 
pedicel short, 5-10 y, colorless, deciduous. 
On Vernonia leiocarpa DC., Guatemala City, Guatemala, February 13, 
1916, II, III, Holway 490 (type); February 15, 1916, II, Il, Holway 4958; 
March 17, 1916, II, III, Holway 585; Mendez, Dept. Guatemala, February 13, 
1917, Holway 860; Antigua, Dept. Sacatepequez, February 4, 1907, Kellerman 
Known only from Guatemala, this very distinct species is easily separated 
from all others on Vernonia, studied by the writer, in the presence of abundant 
Paraphyses with the uredinia and in the tuberculate markings of the teliospores. 
It is accompanied on some of the collections (Holway 495a, Kellerman 6300) 
