CLASSIFICATION 465 



Differs from S. vulgar e in the thin wall of the peridium and 

 umber spore-mass without a violet tinge. The stem is sometimes 

 quite short. 



Under trees. 



S. bovista. — Subsessile ; often irregular in form, 1-2 in. across, 

 wall thin, pliant, almost smooth ; spore-mass oli\'e-brown inter- 

 spersed with thin yellow streaks. 



Distinguished by the almost smooth peridium, and the yellow- 

 streaks in the spore-mass. 



Sandy soil under trees. 



5, geaster. — Sessile, subglobose, 1-2 in. across, wall thick, rigid, 

 almost smooth, brownish, splitting into irregular teeth at the top. 



Sandy ground. 



POLYSACCUM 



Peridium irregularly globose, narrowed into a stout stem ; 

 peridium with numerous cavities containing peridiola. 



P. pisocarpium. — Peridium 1-3 in. across, indistinctly nodulose, 

 olive with a brown tinge, passing down into a stout, stem-like base ; 

 peridiola minute, yellow. 



Sandy ground. Very rare. 



NiDULARIACE.E 



The commonest and most typical representatives of this family 

 are popularly known as " birds'-nest fungi," on account of the 

 general appearance of the peridium or enclosing membrane, with 

 its contained peridiola, or structures containing the spores, to 

 the nest of a bird containing eggs. The structure is somewhat 

 peculiar. In the Gasteromycetes generally the gleba or spore- 

 bearing mass is broken up in the early stage of development into 

 a very large number of small, irregular cavities, by what appear to 

 be veins, giving the gleba a more or less marbled appearance. These 

 veins are in reality walls of tissue, corresponding functionally to the 

 gills of agarics. That is, these walls give origin to the spores, which 

 project into the cavities, which become filled with the spores. Now 

 in the majority of genera, these walls entirely disappear at maturity, 

 leaving the gleba as a dry, dusty mass of spores, as in the puffballs, 

 or, if the walls persist, as in some subterranean species, they do not 

 become hard. In the Nidulariaceae, however, these tramal walls, 

 as they are termed, do persist, and become very hard, and separate 

 from each other, and lie free in the cavity of the gleba. If a section 

 of one of these little hard bodies, or peridiola, as they are called, is 

 examined under the microscope, the interior wiU be seen to contain 

 many spores, which have been produced on basidia, that may be 

 seen projecting from the inner surface of the wall into the cavity 

 of the peridiolum. A somewhat similar formation of peridiola, only 

 2 H 



