Receptacle consisting of thick branched threads; conidia concatenate, at length separating; oospores deeply seated on the mycelium. =Cystopus candidus=, Lév. CRUCIFER WHITE RUST; conidia equal, globose; membrane equal, ochraceous; oospores subglobose, epispore yellowish-brown, with irregular obtuse warts; warts solid.—On Shepherd’s-purse, Cabbages, and other Cruciferæ. Summer. Very common. (Plate X. figs. 198-200, 205-207.) =Cystopus cubicus=, Str. GOATSBEARD WHITE RUST; conidia unequal; terminal cell sterile, larger than the rest; membrane thickened, ochraceous, rarely yellowish; fertile cells shortly cylindrical; membrane hyaline; oospores globose; epispore brown, verrucose; warts hollow, round, or irregular.—On goatsbeard, salsify, and scorzonera. Summer and autumn. Common. (Plate X. figs. 201, 202, 210.) =Cystopus Lepigoni=, De By. SANDWORT WHITE RUST; conidia unequal; terminal cell sterile, globose; membrane thickened; fertile cells subglobose or cylindrical; membrane hyaline; oospores globose; epispore brown, tubercles minute, irregular, very convex, often resembling spines.—On _Spergutaria rubra_. Swanscombe Marshes, September, 1864. (_R. G. Keeley._) PERONOSPOREI, De By. PERONOSPORA, _Casp._ Parasitic threads mostly inarticulate. Spores of two kinds:—1. Acrospores on the tips of the branchlets; 2. Oospores large, globose, on the creeping mycelium. =Peronospora infestans=, Mont. POTATO MOULD; threads of mycelium slender, always destitute of suckers; fertile threads thin, gradually attenuated upwards, with one to five branches, one or more inflated vesicles near the apices of the branches; branches either simple or with short branchlets; acrospores ellipsoid or ovoid; apex furnished with a prominent papilla.—On leaves, stems, and tubers of the Potato, causing the potato-murrain. Very common since 1845. (Plate XIV. fig. 264.) =Peronospora nivea=, Ung. (_P. macrospora_, B.). PARSNIP MOULD; threads of mycelium stout, often torulose; suckers numerous, vesicular, obovate; fertile threads fasciculate, dwarfish, tapering or subulate, or once or twice shortly bifurcate, rarely trifurcate, with one to four horizontal branches near the summit, once, twice, or three times bifurcate; acrospores subglobose or ovoid, with an obtuse papilla at the apex.—On various _Umbelliferæ_. Common and variable. =Peronospora pygmæa=, Ung. (_P. curta_, Berk.). ANEMONE MOULD; threads of mycelium thickened, often constricted and varicose; suckers minute, obovate, or pear-shaped; fertile threads fasciculate (2-5 or more), simple above or divided at the apex into 2-4 short simple branches, or shortly twice dichotomous, or all simple, obtuse, surmounted by 2-4 short spicules; acrospores ovoid or ellipsoid, variable in size; apices broadly and obtusely papillate.—On Wood-anemone. Not uncommon. (Plate XV. fig. 267.)