ipis.] DEVELOPMENT OF AGARICUS RODMANI. 341 



7. The first ridges, or salients, which appear in connection with 

 the hymenophore are the fundaments of the lamellae themselves, 

 and the palisade layer is continuous over their edges as well as in 

 the notch between adjacent salients. 



DESCRIPTION OF PLATES VII.-XIII. 

 PLATE VII. 



Mature and nearly mature plants of Agaricus rodmani showing the 

 double nature of the annulus with its edge grooved; forming an upper and 

 lower limb; the short stem, involute margin of the pileus, etc. X 2/3 diam- 

 eter. For details see text. 



PLATE VIII. 



Mature and very robust plants from parking between sidewalk and street. 

 Real size. See text. 



PLATES IX.-XIII. 



The magnifications of the photomicrographs are as follows: Figs. 3-8; 

 X9 diameters. Fig. 22>', X 10 diameters. Figs, i, 2; X 12 diameters. Fig. 

 32; X 13 diameters. Figs. 34-36; X 20 diameters. Fig. 17; ^^22, diameters. 

 Figs. 15, 16; X 28 diameters. Figs. 21-30, 37-42; X 30 diameters. Fig. 31; 

 X 100 diameters. Fig. 12; X no diameters. Fig. 13; X ISS diameters. 

 Figs. 10, 11; X 160 diameters Fig. 18; X 170 diameters. Figs. 0-14; X 225 

 diameters. Figs. 19, 20; X 250 diameters. 



PLATE IX. 



Fig. I. (No. 18.) Young stage of basidiocarp primordium. 



Fig. 2. (No. 20.) Somewhat older stage of basidiocarp primordium, 

 but still in the undifferentiated stage. 



Fig. 3. (No.-%.) Earliest stage of differentiation in the young 

 basidiocarp, median longitunial section showing a transection of the internal 

 annular hymenophore fundament, the general prelamellar cavity not yet 

 formed. Pileus fundament is above, stem fundament below, and veil fun- 

 dament underneath the hymenophore primordium (see Fig. 9). 



Fig. 4. (No. ^7^.) Longitudinal section of the same basidiocarp, 

 " tangential " to the hymenophore primordium, which is shown as a trans- 

 verse deeply staining area. 



Fig. s. (No. 23^.) Median longitudinal section through a basidio- 

 carp just after the formation of the general, annular, prelamellar cavity. 

 The hymenophore is still in the primordial condition (see Fig. 10) but does 

 not extend down on the surface of the upper part of the stem fundament. 



Fig. 6. (No. -%.) Longitudinal section of the same basidiocarp, 

 "tangential" to the hymenophore and annular cavity (see Fig. 13). 



Fig. 7. (No. ^%.) Median longitudinal section of a basidiocarp 

 just after the formation of the general, annular, prelamellar cavity. The 



