ilacina_
and one _B. verna_, described as having rather delicate colorless
capillitial tubes combined in a loose net, the calcareous deposits about
the enlarged intersections scanty, the spores 12.5 mu.

The description of the fructification as a whole is a condensed
statement of that which describes _P. vernum_, and all taken together
indicates some physarum. See now No. 3 preceding, p. 51.

_P. plumbeum_ Fr. belongs here. It has similar spores, the only
difference is a less calcareous peridium and more scattered habit of
fructification with more nearly regular, depressed-globose sporangia.

_P. cinereum_ Pers. as cited by Link, _op. cit._, is apparently a
badhamia, may be _P. vernum_, while P. _griseum_ is probably the present
species.

14. PHYSARUM VIRESCENS _Ditmar_.

PLATE VIII., Figs. 7, 7 _a_, 7 _b_.

1817. _Physarum virescens_ Ditmar, Sturm, _Deutsch. Fl. Pilze_, I.,
p. 123, Pl. 61.
1875. _Physarum ditmari_ Rost., _Mon., App._, p. 8.
1892. _Physarum ditmari_ Rost., Macbr., _Bull. Lab. Nat. Hist. 1a._,
II., p. 155.
1894. _Physarum virescens_ Ditmar, Lister, _Mycetozoa_, p. 65.
1909. _Physarum virescens_ Ditmar, Torrend, _Flo. d Myx._, No. 207.
1911. _Physarum virescens_ Ditmar, Lister, _Mycetozoa, 2nd ed._,
p. 83.

Sporangia sessile, crowded or heaped in small bunches, a dozen or more
sporangia in one pile, spherical, ovoid or elongate, yellow or greenish
yellow; peridium thin, fragile; capillitium delicate, with rather small,
irregular, yellowish, calcareous nodes; columella none; spores bright
violet, minutely roughened, 7-9 mu.

This species occurs more commonly on moss-tufts, with which it is
frequently con-colorless, or escaped on dead leaves, etc. The peridium
is flecked with calcareous scales or grains stained yellow or green, and
to these the whole fruit owes its peculiar color. The color and
aggregate, heaped sporangia are distinctive macroscopic characters.

In the _Monograph_, p. 113, Rostafinski adopted properly Ditmar's name
for this species. Upon later consideration, in the _Appendix_, p. 8, he
changed the name, writing _P. ditmari_, on the ground that _virescens_
was descriptive of a character to which the species in question
occasionally refuses to conform. Most authors since Rostafinski have
simply accepted his suggestion, so that the species is often entered _P.
ditmari_ Rost. _P. virescens_ is certainly to be preferred. _N. A. F._,
2