2 Massee and Crossland : New Yorkshire Agarics. 



Psilocybe helvola (Schaeff.). 



Pileus 2-4 cm., campanulate then expanded and obtuse, even, 

 glabrous, tawny-ochraceous, disc darkest, the cuticle often 

 cracked into patches near the disc ; flesh thin except at the 

 disc, pallid ; gills adnate then separating - from the stem, broad, 

 rather distant, purplish-umber, clouded, edge white ; spores 

 obliquely elliptical, ends pointed, warted, purplish-brown, 9-10 x 

 5-6 [J. ; stem 4-6 cm. long, 3-4 mm. thick, equal, hollow, fibrillose, 

 often twisted, white or tinged ochraceous, base thickened, downy, 

 white. 



On the ground among grass. Gadeby, Yorks, Y.N.U. 

 Fungus Foray, September 1901. 



This fungus is exactly Agaricus helvolus Schaiffer, pi. 210, 

 and differs from all known species of Psilocybe in the peculiarly- 

 shaped, warted spores. The habit is that of P. sarcocephala, but 

 sufficiently distinct in the very broad, adnate gills and the spores. 



As a personal matter on the part of one of us, I take this 

 opportunity of correcting an error — one only out of many, I fear 

 — that I committed in my ' Fungus Flora.' Fries, in describing 

 Lactarius vellereus, states that the milk, characteristic of the 

 genus, is sometimes absent in this species, and gives as a 

 synonym Agaricus exsuccns Pers., which he considered as the 

 milkless form of L. vellereus. The variety differs not only from 

 L. vellereus in the absence of milk, but also in having the gills 

 and a zone round the apex of the stem tinged with green. The 

 spores are pure white. Of late years many Continental and 

 British mycologists have come to consider this milkless, green- 

 gilled fungus — Lactarius exsuccus, of Otto, W. G. Smith, and 

 others — as the true Russula delica Fries. Dr. Cooke did not 

 agree with this decision, and expressed his reasons for not doing 

 so in ' Grevillea,' XVI., 65. Unfortunately I followed the general 

 opinion, instead of remembering the old adage ' experto crede,' 

 and described the gTeen-gilled fungus as Russula delica Fr. 



Now the Abbe Bresadola, an eminent Italian mycologist, 

 who has paid special attention to this subject, has shown, I trust 

 convincingly, by means of figures, references to literature, etc., 

 that the milkless, green-gilled fungus is the Agaricus chloroides 

 Krombh., and, furthermore, that it is quite distinct from Russula 

 delica Fries; differing in its larger size, pubescent pileus and 

 stem, and in the glaucous-green tinge of the gills. 



As the only difference between Lactarius and Russula consists 

 in the absence of milk in the latter, the green-gilled fungus will 

 henceforth be known as Russula chloroides (Krombh.) Bresadola. 



Naturalist, 



