Some brick spawn used in mushroom beds under the benches of a greenhouse at the New York Agricultural Experiment Station was obtained from an uold and reliable firm of seedsmen in New York City. It was purchased as u American spore culture mushroom, cream white variety. All of the mushrooms produced from this spawn were altogether different from the common mushroom, Psalliota campestris. They were reddish-brown, fibrillose-scaly, and usually of large size. Being unable to determine the species, we sent specimens to Dr. C. H. Kauffman, Ann Arbor, Michigan, for identification. After a careful study of the plants Dr. Kauffman expressed the opinion that they belonged to Psalliota brunnescens, a species described by Peck (4) in 1900. This identification is necessarily uncertain, because, as stated by Duggar (1), the cultivated form of a mushroom may be quite different from its wild form. In a letter dated April 26, 1926, Dr. Kauffman says: Of course it may not be P. brunnescens, but I know of no other species to which it can approach so closely. It certainly should not be considered a variety of P. campestris, P. arvensis, or P. subrujescens, unless cultivation of agarics causes more far-reaching changes than any known in plants and due to cultivation of this kind. It should be noted here that Murrill (3) once wrote as follows concerning Psalliota brunnescens: uMy A[garicus] campester hortensis described and figured in Mycologia for July, 1914, seems very near this species. Previously, Murrill (2) had stated that his variety is often cultivated but is rarely found wild. Our fungus is characterized as follows: Pileus 5-12 cm. broad, convex to convex-expanded, firm, dry, reddish-brown, fibrillosescaly, margin at first incurved and surpassing the lamellae; 41