SummaryIsolations of fungi from twenty-two samples of Illinois soil have been made. The soils ranged in type from pure sand of the shore of Lake Michigan to humus of wooded areas. Samples were taken from cultivated and uncultivated areas, at the surface and at depths of 5, 15, 25, 45, 60, 90 and 120 centimeters.Examination of pure cultures of the fungi yielded thirty-nine species and one variety, belonging to eighteen different genera. In addition, fourActinomycesand several yeasts were observed.Fungi were most numerous at the surface of the soil, decreasing markedly with depth. A few forms, however, were found to be present at depths heretofore unexamined; namely,Actinomycesspp.,Penicilliumsp.,Trichoderma Koningi, andZygorrhynchus Vuilleminiiat 60 centimeters;Penicilliumsp.,Verticillium lateritium, andZygorrhynchus Vuilleminiiat 90 centimeters; andChaetomium subterraneum,Penicilliumsp., andTrichoderma Koningiat 120 centimeters.In tilled areas species ofMucorwere dominant; in untilled areas they occurred only sparsely.In surface soil species ofMucor, AspergillusandPenicilliumwere most numerous; in sub-surface soil,Penicilliumspp.,Trichoderma Koningi, andZygorrhynchus Vuilleminiiappeared more frequently than other forms.The following eight species are herein reported for the first time as occurring in the soil:Chaetomium subterraneumSwift&Povah, sp. nov.,Circinella simplexvan Tiegh.,Mucor griseolilacinusPovah,Myrothecium convexumBerk.,Stysanus mediusSacc.,Trichosporium nigricansSacc. f.lignicola,Trichurus terrophilusSwift&Povah, sp. nov., andVerticillium lateritiumBerk.Chaetomium subterraneumandTrichurus terrophilusare described as new species.The conclusions of previous workers with regard to the genera found most commonly in the soil: namely,Aspergillus, Fusarium, Mucor, Penicillium, Rhizopus, Trichoderma, andZygorrhynchus, are confirmed by the present work.