692.

Canada, New England, New York, Pennsylvania, Ohio, Iowa, Black Hills,
South Dakota.

15. PHYSARUM RUBIGINOSUM _Fries_.

1817. _Physarum rubiginosum_ Fries, _Symb. Gast._, p. 21.

Plasmodium scarlet. Sporangia globose or cylindric, sessile or sometimes
narrowed to a stem-like base as if short-stipitate, olivaceous brown
with sometimes a flush of red; the peridium simple, thin rugulose or
plain, the calcareous scales few, or apparently included; columella
none; capillitium dense, the nodules rather large, angular, rusty brown;
spores dull violaceous, gently roughened, about 10 mu.

A beautiful well-marked species, but evidently rare in North America.
Our only typical specimens are from the gatherings by Mr. Wingate, part
of which is by Lister referred to this species, _Mycetozoa, 2nd ed._, p.
82.

_P. rubiginosum_ Fr. in the _N. A. S._, 1899, is based on certain west
coast specimens now known as _Badhamia decipiens_ Berk.

In Colorado there occurs a plasmodiocarpous form of the species. It has
the characteristic spore and capillitium but in form and habit differs
very decidedly. The fructification is a delicate netted plasmodiocarp,
the tubule about .5 mm., bright red; the peridium simple, cartilaginous,
dehiscent from above, and flecked with just here and there a red
calcareous scale.

Collected at Palmer Lake; _Professor Bethel._

16. PHYSARUM INSTRATUM _Macbr. n. s._

1899. _Physarum thejoteum_ Macbride, _N. A. S._, p. 36, not Fries,
as cited.
1911. _Physarum virescens_ Ditmar, Lister, _Mycetozoa, 2nd ed._,
p. 83.

Sporangia very small, closely crowded on a delicate, more or less
visible hypothallus, often connate, but not superimposed, sub-spherical,
dull orange, brownish or tawny; peridium thin, violaceous, covered with
very minute yellow calcareous scales; columella none; capillitium lax,
sometimes almost wanting; the nodules small, yellowish or brownish,
occasionally confluent; spore-mass violaceous, spores by transmitted
light, violet-tinted, smooth or nearly so, 6-7 mu.

Not uncommon in the Mississippi valley, where it sometimes is passed by
the collector as an immature form of some other species. The appearance
is very characteristic, unlike _P. virescens_ in both habit, size, and
color. Colonies are quite often three inches in length. The most common
habitat seems to be rotten oak, especially fragments of charred logs,
etc.

Ohio, Illinois, Missouri, Iow