388 NORTH AMERICAN FLORA [VoLuME 7 
_ This species resembles Nigredo (?) Celosiae (Dietel & Holway) Arth., except in the posses- 
sion of two-celled teliospores. The two forms are separately maintained for convenience, but 
should eventually be united under one name. 
ON AMARANTHACEAE: 
Achyranthes obovata (Mart. & Gal.) Standley, Oaxaca. 
TYPE LocaLITY: Oaxaca, Mexico, on Achyranthes obovata. 
DisrRipuTion: Known only from the type locality. 
175. Dicaeoma Rivinae (Berk. & Curt.) Arthur. 
Aecidium Rivinae Berk. & Curt. Jour. Linn. Soc. 10: 358. 1869. 
Endophyllum Rivinae Arth. N. Am. Flora 7: 126. 1907. 
Puccinia Raunkaerii Ferd. & Winge, Bot. Tidsskr. 29: 8. 1908. 
Puccinia Rivinae Speg. Anal. Mus. Nac. Buenos Aires 19: 304. 1909. 
O. Pycnia amphigenous, sometimes caulicolous, gregarious on spots with the aecia, honey- 
yellow becoming brown, globoid, 100-150 in diameter; ostiolar filaments short; pycnio- 
spores numerous. 
I. Aecia amphigenous, caulicolous or petiolicolous, gregarious on brownish spots or upon 
larger distorted areas, short-cupulate, 0.3-0.6 mm. across; peridium whitish, the margin erect, 
lacerate; peridial cells rhomboidal, 12-17 by 22-35 u, the outer wall 4-6 » thick, smooth, the 
inner wall thinner, 2-4 u, verrucose; aeciospores ellipsoid or angular, 15-23 by 26-37 y; wall 
golden- or cinnamon-brown, 1.5-2 uw thick, finely verrucose. 
II. Uredinia amphigenous, chiefly epiphyllous, gregarious in small, often concentric 
groups, roundish, small, 0.3-0.7 mm. across,. rather early naked, pulverulent, cinnamon- 
brown, ruptured epidermis noticeable; urediniospores ellipsoid, 17-23 by 23-30 »; wall cinna- 
mou-brown, 1.5 « thick, sparsely and strongly echinulate, the pores 2, sometimes 3, usually 
superequatorial. 
III. Telia chiefly epiphyllous, numerous, gregarious in small groups, roundish or oval, 
0.2-1 mm. across, early naked, pulverulent, chestnut-brown, ruptured epidermis conspicuous; 
teliospores ellipsoid, 22-27 by 29-43 uw, rounded above and below, slightly or not constricted 
at septum; wall cinnamon- or chestnut-brown, 1.5-2y thick, uniform, sparsely verrucose; 
pedicel fragile, 5-10 yu long. 
ON PETIVERIACEAE: 
Rivina humilis L., Cuba; Porto Rico; St. Thomas. 
Rivina octandra 1,., Cuba; Porto Rico. 
TYPE LOCALITY: Cuba, on Rivina octandra. 
DISTRIBUTION: West Indies; also in South America. 
176. Dicaeoma (?) modicum (Holway) Arthur. 
Puccinia modica Holway, Jour. Myc. 10: 164. 1904. 
O and I. Pycnia and aecia unknown. 
II. Uredinia caulicolous and hypophyllous, sometimes also epiphyllous, scattered, roundish 
or oblong, 0.2-0.5 by 0.2-0.8 mm., early naked, pulverulent, cinnamon-brown, ruptured epi- 
dermis noticeable; urediniospores globoid or broadly ellipsoid, 18-23 by 19-26 u; wall golden- 
brown, 1.5-2, thick, finely and closely verrucose, the pores 3-6, scattered or sometimes 
approximately equatorial. 
JII. Telia caulicolous and amphigenous, chiefly hypophyllous, scattered, roundish or 
irregular, 0.2-0.5 by 0.2-1 mm., early naked, rather pulverulent, chestnut-brown, ruptured 
epidermis noticeable; teliospores broadly ellipsoid, 23-29 by 29-35 p, rounded at the ends, 
usually not constricted at septum; wall chestnut-brown, 3-4 » thick, sometimes 5 x, thickened 
up to 7 »-at apex, smooth; pedicel colorless, stout, up to 100 » in length; mesospores common, 
globoid or broadly ellipsoid, 24-29 by 27-32 », the wall 3-5 u thick, thickened up to 7-8 » at 
apex. 
On ALSINACEAE: 
Arenaria alsinoides Willd., Guatemala. 
Arenaria lanuginosa Rohrb., Guatemala. 
Arenaria sp., Oaxaca. : 
TYPE LOCALITY: Etla, Oaxaca, Mexico, on Arenaria sp. 
DistRisvuTIoN: Southern Mexico and Guatemala. 
I_LustRATIONS: Holway, N. Am. Ured. 1: gl. 15, f. 62. 
