On Brassica nigra, Black mustard. Burl., Sept. 1890; J. 748. 

 On Brassica sinapistrum, Charlock. Burl., July, 1898 ; O. 1813. 

 On Dentaria diphylla. Abundant. Burl., June, 1891 ; C. 750. 

 On Lepidium intermedium, Peppergrass. Common. Burl., 1894; 

 J. 749. 



On Raphanus sativus. Radish. Neither common nor very in- 

 jurious. Burl., Sept. 1891 ; J. 752. 



On Sisymbrium officinale, Beaver, July, 1898 ; O. 1817. 



Cystopus Portulacae (DC.) Lev. 



On leaves and stems of Portulaca oleracea, Purslane. Common. 

 Burl., July, 1894; J. 754. 



Cystopus Tragopogonis (Pers.) Schroet. (C. cubicus DeBy.) 



On Ambrosia artemisiaefolia, Ragweed. Burl., Aug. 1892; J. 756. 

 On Tragopogon porrifolius, Salsify. Burl., June, 1890; J. 404. 



Peronospora alta Fuckel. 



On Plantago major, Plaintain. Burl., June, 1891; J. 765. 

 On Plantago Rugellii. Burl., July, 1898; J. and O. 1780. 



Peronospora effusa (Grev.) Rabh. 



On Chenopodium album. Pigweed. Burl., June, 1893; J. 768. 



Peronospora parasitica (Pers.) DeBy. 



On Dentaria laciniata. Common. Burl., June, 1891; J. 769. 

 On Dentaria maxima. Burl., May, 1897; J. 783. 



On Raphanus sativus. Radish. Not common. Burl., Sept., 1894; 

 J. 1367. 



Peronospora Schleideni Ung. 



On Allium Cepa, Onion. Apparently not common, but very de- 

 structive where occurring. Milton, Sept. 1895; J. 773. 



Phytophthora infestans (Mont.) DeBy. 



On Solanum tuberosum. Potato. Common and in favorable seasons 

 very destructive, causing the familiar late blight and rot of the potato. 

 Burl., Sept. 1890; J. 408. 



Plasmopara Halstedii (Farl.) Berl. & DeToni. 



On Bidens cernua. Johnson, Sept. 1893; G. 430. 



Plasmopara obducens Schroet. 



On cotyledons of Impatiens sp. Burl., May, 1891; J. 780. 



