808 THE AGARICACEAE OF MICHIGAN 



5.5-6 micr., smooth, white. CYSTIDIA none. STERILE CELLS 



on edge of gills short, lanceolate, ventricose below. ODOR and 

 TASTE none. 



Gregarious. On the ground, moss and debris under tamarack 

 trees. Ann Arbor. October. Infrequent. 



The plants have the habitat of M. rftetata, but differ from it in 

 the lack of odor, the dark-colored umbo and the microscopic char- 

 acters. The gills are not provided with cystidia as in M. atroal- 

 boidcs and the stem is differently colored. Despite the similarity 

 of the descriptions the two species are very distinct. Our plants 

 differ from Fries' description in that the base of the stem lacks any 

 marked "bulbous-tumid" root, therefore they are only provisionally 

 referred to M. atroalba. 



862. Mycena atroalboides Pk. 

 X. Y. State Mus. Rep. 27, 1S75. 



PILEUS 5-15 mm. broad, acorn-shaped at the very first, then con- 

 ico-campanulate, finally umbonate and margin recurved, striatulate 

 and blackish-fuscous when moist and young, hygrophanous, fading 

 to fuscous or cinereous, and then subsulcate. FLESH very tit in, 

 membranaceous, whitish with a gray tinge. GILLS uncinate-ad- 

 nexed, narrow, close, white, faintly grayish at length, edge entire. 

 STEM slender, 4-10 cm. long, 1-1.5 mm. thick, equal or attenuated 

 upwards, glabrous and even above, hollow, wavy, fragile, shining, 

 terete or compressed, easily splitting lengthwise, dark bluish or 

 blackish-gray at apex, tinged gray or fuscous elsewhere, sometimes 

 connate with cottony fibrils below. SPORES 7-9 x 5-6 micr., broad- 

 ly elliptical, smooth, white. CYSTIDIA numerous on sides of gills, 

 subcylindrical, slightly ventricose below, obtuse, 75-85 x 7-8 micr. 

 STERILE CELLS none. 



Solitary or subcaespitose, on decayed wood and mosses, in woods 

 of hemlock, beech, etc. New Richmond. August-September. In- 

 frequent. 



Manifestly related to 31. atrocyaneus Fr. and 31. atroalbus Fr. 

 M. atrocyaneus is said to have the gills joined to a collar and dis- 

 tant, while the pileus is deeply sulcate. From 31. atroalbus, M. 

 atroalboides differs in possessing abundant cystidia on the sides of 

 the gills and by its more uniformly colored pileus. A form occurs 

 with pileus cylindric when very young and at first dotted with 

 white, scattered, silky fibrils on the surface ; its cystidia are thicker, 



