Witson: NortH AMERICAN PERONOSPORALES 79 
1709), Stanfield ; Virginia, Heller 1023 ; Mexico, Berlan- 
dier ; Porto Rico, Millspaugh. 
~ Amaranthus tristis L., Grenada, Broadway ; St. Croix, Rick- 
secker 109. 
Amaranthus viridis L., Florida, * Hitchcock 298, Nash 2179. 
Cladothrix lanuginosa (Moq.) Nutt., Kansas, Hitchcock 431 ; 
New Mexico, Wooton ; Mexico, Berlandier. 
Cyathula lappulacea Mog., New York, Peck (Roum, Fungi 
Sel. 2863). 
Also reported from within our limits on the following additional 
hosts: Acnida cannabina L., A. tamariscina (Nutt.) Willd., Ama- 
ranthus crispus (Lesp. & Thev.) Braun, and A. hybridus paniculatus 
(L.) Uline & Bray. 
Type Loca.ity: Sicily, on Amaranthus Blitum 1. 
Distrisution: Vermont to Washington, Mexico, Florida and 
the West Indies. Also in South America, Europe, Asia and 
Africa. 
tr. ALBUGO PLATENSIS (Speg.) Swing. Jour. Myc. 
7: 113. 1892 
Cystopus platensis Speg. Rev. Argent. Hist. Nat. 1: 32. 
Hypophyllous, sori at first pallid, later surrounded by a pur- 
plish line, irregular in outline, I-5 m 
prominent ; conidiophores cylindric, about 40-45 
elliptic, 20-22 x 18-204, very light-yellow, the membrane with 
an equatorial thickening which is. darker-colored in the smaller 
terminal conidium ; odspores borne in the leaves of the host, very 
opaque, very dark-brown, globular, 5 5-85 p, averaging 60 p, finely © 
reticulate, areolae about 4 /. A ee 
This species is very closely related to A. Buu, from which it 
is, however, quite distinct. The conidia of A. Bliti are hyaline 
and white in mass while those of 4. platensis are slightly colored, 
appearing light-yellow in mass while the apical conidium has a 
darkened equatorial band. The. oospores, which are produced in 
the leaves of the host in both species, are very similar and at first 
sight indistinguishable. Those of A. platensis are very dark- 
brown, so opaque that until treated with HCl they appear as black 
grains, and are finely reticulate, while those of A. Bit are lighter 
in color, less opaque, slightly smaller in size and more coarsely 
reticulate, the areolae being from one third to one half larger. 
