ORDER AGARICALES 509 



visible as patches of tissue, as in A. muscaria, where the veil does not keep 

 pace with the remainder of the expanding pileiis and so is torn to pieces. 

 On the other hand if it does keep pace in its growth it is detectable as a 

 thin fibrous layer or cuticle of some other type. Around the foot of the 

 stipe the universal veil is left as a loosely or closely adhering cup, the 

 volva. In angiocarpic forms like Agaricus there is no volva, as the rupture 

 is so low doAvn that no free basal portion of the veil is distinguishable. In 

 angiocarpic forms with an annulus or secondary veil this arises as a sheet 

 of tissue below the circular hymenial cavity, either separating this cavity 

 from the outside air below or, if attached high on the stipe, sheathing the 

 upper part of it. The annulus may be simple (as in Agaricus campestris) or 

 of two distinct layers (as in A. arvensis). It may break free from the edge 

 of the pileus and also from the stipe to form a movable ring (as in Lepiota 

 procera) or at one or the other place, leaving a ring attached to the stipe 

 or broken sheets or threads attached to the edge of the pileus (a cortina). 

 In pseudoangiocarpic forms the annulus, as in the Boletaceae, may be 

 composed of tissues from the stipe, that gi-ew out and attached themselves 

 to the incurving pileus margin or of tissues from the edge of the pileus that 

 became attached to the surface of the stipe. The truly gymnocarpic forms 

 show neither annulus nor volva nor patches or cuticular structure on the 

 pileus that represent in any manner the remnants of a universal veil. 



Reijnders (1933) assembled from literature and from his own investi- 

 gations a list of 79 species of Agaricaceae of which the mode of develop- 

 ment of one is doubtful, 21 gymnocarpic, 2 pseudoangiocarpic and 55 

 angiocarpic. Heim (1937) added two pseudoangiocarpic species to this 

 list. It must be noted that some writers list the latter type of development 

 as gymnocarpic so that probably there should be in Reijnders' hst a 

 higher proportion of species with pseudoangiocarpic type of development. 

 All of the Ochrosporae and Melanosporae among the 81 species concerned 

 are angiocarpic ; of the four Rhodosporae listed one is pseudoangiocarpic 

 and three gymnocarpic. Of the 41 Leucosporae 19 are angiocarpic, 19 

 gymnocarpic, 2 pseudoangiocarpic and 1 doubtful. If the angiocarpic 

 species, following Singer (1936) and others, are the more primitive, arising 

 from the Gasteromycetes, it is apparent that the Agaricaceae with colored 

 spores are the more primitive and those with white or pink spores further 

 from the ancestral forms. If the light-spored forms are considered the 

 more primitive then the angiocarpic genera in general are further ad- 

 vanced in evolution. The peculiar type of hymenium of Coprinus and of 

 some species of Pscudocoprinus, with broad paraphyses and the more 

 slender basidia arranged in squares at the corners is not found except in 

 these and perhaps a few other black-spored species. Aside from this ar- 

 rangement of the basidia and paraphyses these two genera have certain 

 other specialized structures that appear far from primitive. In the stout. 



