_Physarum berkeleyi_ Rost., List., _Mycetozoa_, p. 48, in part.
1899. _Physarum galbeum_ Wing., Macbr., _N. A. S._, p. 53.
1911. _Physarum galbeum_ Wing., List., _Mycetozoa, 2nd ed._, p. 59.

Sporangia scattered, globose, stipitate, often nodding, golden yellow,
the peridium exceedingly thin, breaking up into patches on which the
yellow lime granules are conspicuous; stipe non-calcareous, pale brown
or amber-colored, longitudinally wrinkled, about one and one-half times
the diameter of the peridium; columella none; hypothallus none;
capillitium dense, extremely delicate, the nodes only here and there
calcareous, the lime knots when present small, angular, yellow;
spore-mass pale brown; spores almost smooth, lilac- or violet-tinted,
7.5-10 mu.

Distinguished among the small delicate species with which it will be
naturally associated, by the yellow, richly calcareous wall of the
globose sporangium and the almost limeless capillitium. The stipe is
hollow and contains irregular masses of refuse granular matter, but no
lime so far as we have been able to discover. _P. flavicomum_, to which
the species is related most closely, differs in having the wall
non-calcareous, iridescent, as well as in the color throughout; the
character of the capillitium, in which lime is abundant; the absence of
refuse-matter in the stem.

Pennsylvania, Iowa, Minnesota.

50. PHYSARUM TENERUM _Rex._

1890. _Physarum tenerum_ Rex., _Proc. Phil. Acad._, p. 192.
1894. _Physarum polymorphum_ Rost. var. _obrusseum_, Lister,
_Mycet._, p. 48.
1899. _Physarum obrusseum_ (Berk. & C.) Rost., Macbr., _N. A. S._,
p. 52.
1911. _Physarum tenerum_ Rex., List., _Mycetozoa, 2nd ed._, p. 52.

The peridium thin, membranaceous, thickly studded with circular,
flattened, yellow granules of lime; stipe long, slender, subulate,
opaque, pale brown, striate and black below, pale yellow above;
columella none; capillitium yellow or white, delicate, forming a loosely
but regularly meshed network with numerous small round or rounded
granules at the intersections; spores dark brown, delicately warted, 7-8
mu.

This delicate physarum, very fragile and evanescent, seems to be
distinct, by reason of its characteristic rounded lime granules, from
any similar, stipitate species. It varies a little according to
locality. Ohio specimens are a little larger and have thicker and more
calcareous stipes than is usual in those from Philadelphi