ORDER AGARICALES 507 



gills protrude as they develop. According to Levine (1922) the early ap- 

 pearance of the annular cavity is an artefact and the openings arise first 

 between the developing gills and only later below their edges if at all. In 

 Coprinus the gills remain in contact with the upper part of the stipe until 

 the spore fruit is nearly mature and the pileus begins to expand. Eventu- 

 ally this circular cavity is bounded on the inner side by the portion of the 

 spore fruit that becomes the stipe, and by the flattening of the pileus a 

 circular break next to the stipe permits the pilear expansion so that the 

 gills now become exposed to the air and shed their spores. (Fig. 170 H-I.) 

 In these forms the surfaces destined to bear the hymenium arise within 

 the pileus while in the other two types it was at first exposed to the air 

 and became ultimately enclosed only in the pseudoangiocarpic type of 

 development. For details as to gymnocarpic and pseudoangiocarpic de- 

 velopment consult Kiihner (1925b, 1926), Blizzard (1917), Douglas 

 (1918), Walker (1919), Reijnders (1933), Heim (1936b, 1937), and others, 

 and for the angiocarpic type Atkinson (1906, 1914, 1915, 1916), Levine 

 (1922), Douglas (1916, 1920), and some of the foregoing hst. 



The 5000 to 8000 species of the Agaricaceae are divided into 50 to 112 

 genera, according to the ideas of the various students of the group. Fries 

 (1821) recognized only two genera in the limits of the family as here 

 treated, Agaricus and Schizophyllum. Killermann (1928) recognized 66 in 

 the second edition of Engler and Prantl. Singer (1936) included about 112 

 genera. More often these are all included in only one family but more 

 recently Heim, Singer, and others have divided them into 10 or 11 fam- 

 ilies. It will probably be desirable to make a segregation, but until there is 

 greater agreement as to just what the generic distinctions must be and 

 how the families should be delimited the author will be conservative and 

 include all in one family. 



Fries divided his genus Agaricus into 38 tribes, most of which were 

 later recognized as genera by him and by other mycologists. The primary 

 basis of the division into two genera was a sphtting of the lamellae in 

 Schizophyllum and the entire lamellae in Agaricus. The latter was divided 

 into series on the basis of spore color : white, rose, ochraceous, rusty, purple- 

 brown, and black. In the "Sylloge Fungorum" (Saccardo, 1887) these 

 primary subdivisions were called respectively Leucosporae, Rhodosporae, 

 Ochrosporae (including both ochraceous and rust-colored spores), Melan- 

 osporae (including both purple-brown and black spores). The location of 

 the stipe (central, eccentric, or lateral), the presence or absence of annulus 

 and volva, the shape of the pileus, the character of the stipe, the relation 

 of lamellae to stipe (i.e., free, attached, decurrent, etc.), the color of the 

 gills and of the pileus were all characters used in dividing these spore-color 

 groups into the lesser groups (tribes or genera) . All these characters were 

 largely external and did not take into consideration the internal structures 



