PLATE 28 
A. —A small ring formed by Agaricus campestris, showing a total of 29 mushrooms, 
the largest being about 10 cm. in diameter. The footpath in the upper right portion 
of the illustration has no connection with the ring. Akron, Colo., June 17, 1916. 
B. —A large ring of Calvatia polygonia, showing 14 fruiting bodies, the largest of 
which are 33 cm. in diameter. The diameter of this incomplete ring was about 100 
meters. The puffballs occurred at the edge of a very green area of short grass. No 
difference in composition of the native was noted, but the deep-green color and the 
somewhat more luxuriant growth of the short grasses just inside the fruiting zone was 
especially noticeable. Six miles southwest of Yuma, Colo., July 26, 1907. 
