ddish alutaceous;
capillitium usually abundant, of slender, delicate pale or colorless
threads, little branched, and smooth; spores violaceous-brown, minutely
roughened, 8-9 mu.

A very beautiful species occurring at the same time as the preceding and
in similar situations. All our specimens from the west are on dead
leaves of oak; some eastern gatherings are on moss. Easily recognized
when fresh by its delicate pink or roseate color; weathered specimens
are white, and might be confused with forms of _D. reticulatum_, but the
sporangia in the present species are less flattened and only rarely in
special situations run off to linear or plasmodiocarpous shapes
characteristic of _D. reticulatum_.

Not common, although widely distributed from east to west. New England,
New York, New Jersey, South Carolina, Ohio, Illinois, Iowa, Nebraska,
California (_Harkness_), Washington, Oregon.

8. DIDERMA NIVEUM (_Rostafinski_) _Macbr._

PLATE XVIII., Fig. 11 and 11 _a_

1875. _Chondrioderma niveum_ Rost, _Mon._, p. 170.
1877. _Diderma albescens_ Phillips, _Grev._, V., p. 114.

Sporangia gregarious, scattered, or more often crowded, sessile,
depressed-spherical, sometimes ellipsoidal or elongate, white, the outer
peridium crustaceous, chalky, smooth and fragile, the inner distinct,
delicate, ochraceous; hypothallus scant or none; columella well
developed, globose or hemispherical, orange-tinted or ochraceous;
capillitium abundant, made of threads of two sorts, some purplish or
dusky, with pale extremities, uneven, others more delicate and
colorless, and with wart-like thickenings, all sparingly branched;
spores violet-brown, minutely roughened, 9-10 mu.

This species is not common. From Colorado we have fine specimens typical
in every way. Specimens from Washington are flat so far as at present at
hand; probably represent _D. deplanatum_ (R.) List., which the last
named author regards as varietal of the present species, entering it and
_D. lyallii_ as sub-species 2 and 1 respectively. _D. deplanatum_ may
perhaps be best so disposed of; but _D. lyallii_ is distinguished at
sight, as well as by microscopic characters, spores nearly twice as
great, rougher and different in color.

9. DIDERMA CINEREUM _Morg._

1894. _Diderma cinereum_ Morg., _Myx. Mi. Val._, p. 70.

Sporangia gregarious, more or less crowded or even confluent,
sub-globose, only slightly depressed, ashen white; the peridium not
obviously double, ver