I9I5.] DEVELOPMENT OF AGARICUS RODMANI. 313 



lower limb of the annulus in A. rodmani is merely a part of the 

 marginal veil is clearly seen in the sectioned plants shown in the 

 lower groups of Plate VII., where the connecting portion between 

 the two limbs is clearly differentiated from the surface of the stem 

 with which it is in contact, a situation very different from that in 

 Amanita where the volva has no such relation to the annulus. 



Comparison of Agariciis rodmani with other Species of Agaricus. 

 — This extensive peeling, or ripping upward of the annulus from the 

 lower part of the stem in Agaricus campestris is the cause of the 

 more extensive, i. e., broader, veil and annulus than is characteristic 

 for Agaricus rodmani. Peck regards this species as intermediate 

 between Agaricus campestris and A. arvensis,'^ resembling the former 

 in size, shape and general appearance ; the latter in the " whitish 

 primary color of the lamellse," in the occasional yellowish tints of 

 the pileus, and the occasional rimose under surface of the annulus. 

 The robust character of the annulus of Agaricus rodmani and the 

 thick flesh of the pileus margin crowded by epinastic growth against 

 the stem deepens and widens the groove on the edge of the annulus. 

 This, together with the very short stem, in comparison with the 

 longer stem of Agaricus campestris and A. arvensis, is, I think, 

 largely responsible for certain dift'erences in the character of the 

 under surface of the annulus in the different species. In the species 

 with the longer stem more stretching of the stem occurs and the 

 annulus (or veil) is ripped upward from a greater extent of the 

 stem surface. The radiately grooved character of the under surface 

 of the annulus, in certain species {A. arvensis Schultz, A. ahrupti- 

 bulbus Pk., A. placom,yces Pk., A. hcemorrhoidarius Schultz), or the 

 coarsely floccose or scaly character in certain others {Agaricus 

 subrufescens Pk., A. augustus Fr., or both features contained in 

 some) is largely due to the fact that this part of the annulus is 

 stripped from the stem and then brought under greater tension than 

 the upper surface as the expansion of the pileus stretches the veil 

 outward. All things considered Agaricus rodmani is much more 

 closely related to Agaricus campestris than to any other of the 

 species. It is very probably identical with Agaricus campestris var. 



6 N. Y. State Mus. Nat. Hist. Rept., 36, 45, 1885. 



