1250 Wisconsin Academy of Sciences, Arts and Letters. 
sometimes scanty or lacking 1 ; columella variable, sometimes very 
small, inconspicuous, sometimes large globose, ellipsoidal, even 
pedicellate; capillitium abundant, brown or purplish-brown, 
branching and occasionally anastomosing to form a loosely con¬ 
structed superficial net; spores globose, delicately spinulose, 8/*.” 
In his “key” to the genus Diderma , Macbride gives the spores 
as 8— 10m, in diameter. He adds that this species seems rare 
in this country ; that the only specimens so far are from Iowa; 
that it is distinguished by small spores and general snow-white 
color. 
Lister says in part: “The outer wall is egg-shell like, com¬ 
posed of globular lime-granules l-2.u in diameter; spores dark 
purplish brown, spinulose, 10-14/*. in diameter.” 
Massee adopts the name CJiondrioderma globosum Eost. He 
says the inner wall is cinereous, often iridescent; spores 8-10/a. 
I find most of the characteristics like those described above. 
The sporangia are noticeably two-walled, the outer wall at a 
distance from the inner ; the inner wall, while not noticeably 
bluish, yet is iridescent when held in sunlight; the columella is 
generalv white and varies in size even in adjoining sporangia; in 
one collection the hypothallus is abundant, in another it is scanty; 
the spores are from 8 to 12/t in diameter, none larger, and most 
of them 10/x, dark purplish, and distinctly spinulose. 
One group was found at the St. Louis Eiver, opposite New 
Duluth, August 2, 1897, on wood burned to charcoal; another at 
Eagle Heights, near Madison, August 6, 1904, on green moss 
and dead oak leaves and twigs. 
Diderma crustaceum Peck. 
1871. Diderma crustaceum Peck, Rep. N. Y. Mus., XXVI., p. 74. 
Macbride: “Sporangia closely crowded or superimposed, in a 
cushion-like colony, creamy-white, globose, imbedded in the sub¬ 
stance of the hypothallus, the outer peridium smooth, delicate 
cmsfaceous, fragile, remote from the blue iridescent inner mem¬ 
brane; hypothallus prominent: columella variable, generally 
present, globose; capillitium dark colored, the threads branching 
and combining to form a loose net: spore-mass black, spores by 
transmitted light dark violaceous, delicately roughened, 12-15/x.” 
Lister classes this species with D. globosum, but Macbride says 
