Witson: NortH AMERICAN PERONOSPORALES 79 
1709), Stanfield ; Virginia, Heller 1023 ; Mexico, Berlan- 
dir; 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 Moq., New York, Peck (Roum. Fungi 
Sel. 4863). 
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. 
Tyre rocatity: Sicily, on Amaranthus Blitum L. 
DistrisuTion: Vermont to Washington, Mexico, Florida and 
= est Indies. Also in South America, Europe, Asia and 
frica 
11. ALBUGO PLATENSIS (Speg.) Swing. Jour. Myc. 
we iss, 1eg2 
Cystopus platensis Speg. Rev. Argent. Hist. Nat. 1: 32. 1891. 
_ Hypophyllous, sori at first pallid, later surrounded by a pur- 
plish line, irregular in outline, I-5 mm., scattered or gregarious, 
Prominent ; conidiophores cylindric, about 40-45 X I15/; conidia 
elliptic, 20-22 x 18—20 u, 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 
°paque, very dark-brown, globular, 55-85 4, averaging 60 #, finely 
Feticulate, areolae about 4 /2. sa 
This species is very closely related to A. Bit, from which it 
is, however, quite distinct. The conidia of A. Biiti are hyaline 
and white in mass while those of A. platensis are slightly colored, 
appearing light-yellow in mass while the apical conidium has bs 
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. p/atensis are very dark- 
brown, SO opaque that until treated with HCl they appear as black 
Stains, and are finely reticulate, while those of A. Biiti are lighter 
en, Color, less opaque, slightly smaller in size and more coarsely 
__ ‘Fettculate, the areolae being from one third to one half larger. 
