diameter,
yellow shading into white, orange or olivaceous, smooth or rugulose,
stipitate; stipe stout, smooth, .5-1 mm. high, yellow or orange above,
white below, cylindric, lime-stuffed; columella large, sub-globose or
clavate, yellow; capillitium either of very slender pale yellow,
threads, branching at acute angles and anastomosing or of broad, yellow
simple or forked strands, persistent after spore-dispersal; nodules few,
small, linear or fusiform; spores purple-brown, spinulose, 10-12 mu.

This species, originally described from England and northern Europe has
more recently been identified in material sent by Professor Sturgis from
Colorado. In description the form is well marked; evinces apparently
great variation alike in form, color, and structure.

The material we have, however, is poor, badly weathered.

The general plan of structure corresponds very well with Fries' idea of
his genus Tilmadoche, although the present species would seem, by very
grossness, strangely out of place with the tilmadoches. But the
singular, didermoid, evenly branching, threads of the capillitium,
bearing their slender spindle-shaped burdens of lime are very
suggestive; it is a diderma gone wandering into the camp of the
physarums if one may judge from Miss Lister's graphic plate.

The specific name selected for this peculiar form has once before done
service, but apparently for something quite dissimilar. Schumacher,
_Enum. Pl. Saell._ II., p. 199, has _P. luteo-album_. Fries thinks he
had a perichaena on hand; at any rate, not a physarum, and makes
Schumacher's combination a synonym for _Perichaena quercina_ Fr., which
Rostafinski in turn makes synonymous with _P. corticalis_ (Batsch) R. If
"once a synonym always a synonym" be esteemed good taxonomic law, this
species must one day have another name. The present author, unwilling to
change his colleague's preference in this case, nevertheless begs to
suggest that such a binomial as _P. listeri_ would probably at once make
future history of the species less eventful, and honor the memory of
England's latest and most distinguished student of the group he loved.

28. PHYSARUM NUCLEATUM _Rex._

1891. _Physarum nucleatum_ Rex., _Proc. Phil. Acad._, p. 389.

Sporangia gregarious, spherical, 1/2 mm., white, stipitate; peridial
wall membranaceous, rupturing irregularly, thickly studded with rounded
white lime-granules; stipe about 1 mm., subulate, yellowish-white,
rugose; columel