Witson: NortTH AMERICAN PERONOSPORALES 77 
10. ArsuGo Britr (Biv.) Kuntze, Rev. Gen. Pl. 
2: 658. 1891 
Uredo Bhti Biv. Stirp. Rar. Sicilia 3: 11. 1815. 
Cacoma Amaranthi Schwein. Trans. Am. Phil. Soc. II. 4: 292. 
1832. 
Cystopus Bliti de Bary, Ann. Sci. Nat. 1V. 20: 131. 1863. 
Cystopus Amaranthi Berk. Grevillea 3: 58. 1874. 
Cystopus Amaranthacearum Zalew. Bot. Cent. 15: 223. 1883. 
Cystopus Cyathulae Winter; Roum. Rev. Myc. 11: 66. 1889. 
Sori amphigenous, white or very light-yellow, prominent, sub- 
superficial, rounded, sometimes confluent, I-10 mm. ; conidiophores 
hyaline, cylindric, about 15 x 60; conidia hyaline, elliptic, the 
terminal smaller, globular; the membrane with an equatorial 
thickening, 8-15 x 15-204; oOspores produced in the leaves of 
the host, dark-brown, 50-60 », averaging 55/4; epispore coarsely 
reticulate, areolae 6-8 yu. 
According to Zalewski (/. c.) there are two species of A/bugo 
on the genus Amaranthus, the first, Cystopus Bliti, being confined 
to Amaranthus Blitum, while the second, C. Amaranthacearum, . 
infests the other species of the genus. The points of distinction 
are confined to the odspore and are of questionable value, although 
their reliability could not be disproved on account of a lack of 
authentic European material. The odspores of C. Blt are said 
to be formed only on the stem of the host, to vary from light- to 
dark-brown in color and to have irregular reticulations. Those 
of C. Amaranthacearum are borne in the leaves of the host, are of 
a uniform dark-brown and are regularly reticulate. ine ony 
specimen at hand on undoubted Amaranthus Blitum contains a 
few detached leaves with conidia only. That the place of ee 
production cannot be regarded as of taxonomic value is evident, as 
this varies with the host in A. candida and in the same host in 
A. Portulacae. The color of the oospore depends entirely upon 
Maturity and may show remarkable variation just as do those » 
the present species in all specimens examined. The pattern o 
the reticulations cannot be taken as a taxonomic character unless 
accompanied by other marked distinctions, as Pe peters i Pe 
tically the same, or at most a modification of the same oy = 
tern, in 4. Bliti, A. platensis, and A. Portulacae. In all of these 
