eous, 8-9 mu.

Reported in the United States so far from Maine, Pennsylvania, Ohio, and
Illinois.

The sporangia are very small, but beautiful, delicate little structures,
found on the bark of living red oak in this country; in Norway it seems
to have been seen first on a dead polyporus. Its minuteness doubtless
causes it to be generally overlooked, _N. A. F._, 2498.

=3. Lamproderma= _Rostafinski_

1873. _Lamproderma_ Rostafinski, _Versuch_, p. 7.

Sporangia stipitate, globose, or ellipsoid; columella cylindric or
inflated or clavate at the apex, scarcely attaining half the height of
the peridium; peridium shining with metallic tints, deciduous, except
where, at the base of the columella, it forms a ring around the stipe;
capillitium rising in tufts or by simple branches from the columella,
the threads regularly forked, generally united into a net.

The lamprodermas are distinguished from the comatrichas, to which they
are most nearly allied, by the arrangement of the capillitium, its
development from the apex only of the columella, the continuation of the
stipe within the peridium. In other words, the peridium leaves the stipe
some distance below the point where the lowest capillitial branches take
origin. In mature specimens the peridium has often entirely disappeared,
its only trace, a collar, more or less distinct, around the stipe,
marking the beginning of the columella. Nevertheless the peridium is far
more persistent than in any comatricha, and shows in yet greater
brilliancy the wondrous metallic tints and iridescence of _Comatricha_
and _Diachaea_. Older authors, so far as can be seen, distributed the
species between _Physarum_ and _Stemonitis_.

=Key to the Species of Lamproderma=

_A._ Peridium metallic blue.

_a._ Stipe short, stout.

1. Capillitium tips colorless 5. _L. violaceum_

_b._ Stipe long, slender.

1. Capillitium of dark, tapering, oft-united
threads 3. _L. columbinum_

2. Capillitial threads rigid, dark brown,
seldom united 4. _L. scintillans_

_B._ Peridium not blue, silvery.

_a._ Stipe long, slender.

1. Capillitium very intricate, forming a
compact net 6. _L. arcyrionema_

2. Capillitium of rigid dark brown threads 1. _L. physaroides_

_b._ Stipe short, heads large, 1