ooo Capillitium nodes pure yellow.

x. Capillitial threads yellow 49. _P. galbeum_

xx. Capillitial threads hyaline 50. _P. tenerum_

x.x.x. Peridium iridescent.

+ Capillitium persistent 51. _P. flavicomum_

++ Capillitium less persistent, larger 52. _P. bethelii_

SECTION II. TILMADOCHE

I. aethalioid, gyrose or irregular 53. _P. gyrosum_

II. Fructification stipitate.

1. Sporangia irregular, often convolute, involved 54. _P. polycephalum_

2. Sporangia simple, nutant, discoidal.

_a._ Thin-walled, grey or white. 55. _P. nutans_

_b._ Vari-colored, yellow, greenish, orange, etc. 56. _P. viride_

1. PHYSARUM SERPULA _Morgan._

PLATE IX., Figs. 6, 6_a_, and 6_b_.

1831. _Physarum reticulatum_ Alb. & Schw., Schweinitz, _N. A. F._, No. 2295.

1885. _Physarum gyrosum_ (Rost.) Wingate, Ellis, _N. A. F._, No. 1396.

1892. _Physarum gyrosum_ Rost., Ma.s.see, _Mon._, p. 307.

1892. _Cienkowskia reticulata_ Rost, Macbr., _Bull. Nat. Hist. Iowa_, II., 2, p. 150.

1894. _Badhamia decipiens_ Berk., Lister, _Mycetozoa_, p. 33, in part.

1896. _Physarum serpula_ Morg., _Cin. Soc. Nat. Hist._, p. 101.

1899. _Physarum serpula_ Morg., Macbr., _N. A. S._, p. 29.

1911. _Physarum serpula_ Morg., Lister, _Mycetozoa, 2nd ed._, p. 81.

Plasmodiocarp repent, reticulate, forming anon lines, circles, dots, etc., venulose pale yellow, ochraceous, at length whitish, the peridium thin, membranaceous, simple, fragile, but withal persistent, below united with a hypothallus which is more or less widely produced; capillitium rather scant, but abundantly charged with polygonal nodules of lime, yellow; spore-ma.s.s black; the spores, by transmitted light, violaceous, warted, globose, 10-13 . Plasmodium, at maturity, greenish-yellow.

A very distinct species not likely to be confused with anything else, although in description, so far as concerns external characters, suggesting _Cienkowskia reticulata_. The two forms are not at all alike when placed side by side. For details as to the difference, see the description of the species last mentioned.

Apparently not rare in eastern United States, Pennsylvania, Virginia, Ohio, Iowa.

In 1805, Albertini and Schweinitz, _Conspectus Fungorum_, p. 251, t. 7, Fig. 2, described as _Physarum reticulatum_, a European form which became the basis of Rostafinski's genus _Cienkowskia_; see under that genus. Later, 1829, Schweinitz discovered in America a physarum-looking specimen which he took to be the same thing, and accordingly placed in his herbarium under this name, and entered _N. A. F._ 2295. Rostafinski further renamed another Schweinitzian species _Fuligo muscorum_ calling it, _Mon._, p. 111, _Physarum gyrosum_. Wingate and Rex apply in Ellis, _N. A. F._, this latter name to No. 2295 of Schweinitz. Such a reference is a mistake, judging from Rostafinski's descriptions and from the description and figure of Albertini and Schweinitz (_Consp. Fung._, p.

86, t. 7, I), and by the testimony of Lister. For further concerning Rostafinski's species, see under _Physarum gyrosum_, p. 111, _Mon._

2. PHYSARUM LATERITIUM (_Berk. & Rav._) Rost.

1873. _Didymium lateritium_ Berk. & Rav., _Grev._, II., p. 65.

1875. _Physarum ditmari lateritium_ Rost., _Mon._, _App._, p. 9.

1879. _Physarum inequale_ Peck, _Rep. N. Y. Mus._, x.x.xI., p. 40.

1892. _Physarum chrysotrichum_ Berk. & C., Ma.s.see, p. 300.

1894. _Physarum inequale_ Peck, Lister, _Mycetozoa_, p. 60.

1896. _Physarum lateritium_ (Berk. & Rav.) Morg., _Jour. Cin. Soc._, p. 95.

1899. _Physarum lateritium_ (Berk. & Rav.) Morg., Macbr., _N. A. S._, p. 33.

1911. _Physarum lateritium_ Morg., List., _Mycetozoa, 2nd ed._, p. 82.

Plasmodium scarlet. Sporangia gregarious, sessile, globose or sub-globose, or sometimes plasmodiocarpous, yellowish or orange, everywhere, when fresh, spotted with minute scarlet granules; the peridium thin, more or less rugulose; columella none; capillitium delicate, generally yellow, with nodules conspicuous, yellow or reddish; spores violet-brown in ma.s.s, by transmitted light pale violet, minutely roughened, 7-9 .

A well-marked species easily recognized by the characters cited. The extent of lime deposit at the capillitial nodes varies; sometimes very little. This accounts for Berkeley's generic reference. On the other hand, Lister makes the rounded lime knots "each knot with a red centre surrounded by yellow, round, lime-granules" diagnostic. This pied condition does not come out in any of our specimens. The capillitium in broken specimens soon fades, tends to white, etc.

New York, Pennsylvania, Ohio, Colorado, and south. Ceylon, Java, Brazil.

3. PHYSARUM VERNUM _Somm._

1829. _Physarum vernum_ Somm., Fries, _Syst. Mycol._, III., p. 146.

1875. _Physarum cinereum_ (Batsch), Rost., _Mon._, p. 102, in part.

1875. _Badhamia verna_ Rost., _Mon._, p. 145.

1894. _Badhamia panicea_ Rost., List., _Mycetozoa_, p. 34.

1899. _Physarum cinereum_ (Batsch) Rost., Macbr., _N. A. S._, p. 34 (in part).

1911. _Physarum vernum_ Somm., Lister, _Mycetozoa, 2nd ed._, p. 75.

"Plasmodium white." Sporangia sessile, generally plasmodiocarpous white, nearly smooth; peridium more or less testaceous not scaly, but breaking irregularly; capillitium densely calcareous, the nodules angular, branching, sometimes united to form a pseudo-columella; spores dusky violaceous, rough, 10-12 .

Sommerfeldt's description quoted by Fries, _l. c._, evidently concerned a less calcareous phase. Fries by his annotation relieves somewhat the reader's uncertainty.

Rostafinski calls this a badhamia but describes a physarum, and the form has, as is believed, been consistently confused with _P. cinereum_ by every student of the group from the days of DeBary until now. In the second edition of the _Mycetozoa_, Lister clears the situation by transferring the species to _Physarum_, and calling attention to spore-dimensions. The fact is, the species in external appearance so much resembles _P. cinereum_, that the unaided eye cannot distinguish one from the other. Curiously enough, Rostafinski describes the form he had before him as "one of the rarest." Doubtless had he gone back to his specimens of _P. cinereum_ he had found plenty, for in Europe it seems abundant everywhere. In this country it is _P. cinereum_ as now defined, that is rarer, although not uncommon. From all connection with _Badhamia_, as representing _B. panicea_ it should, as would appear, be withdrawn once for all.

4. PHYSARUM SINUOSUM (_Bull._) _Weinm._

PLATE VIII., Figs. 6 and 6_a_, and PLATE XIX, Fig. 15.

1791. _Reticularia sinuosa_ Bulliard, _Champ._, p. 94; t. 446, Fig. 3.

1796. _Physarum bivalve_ Persoon, _Obs. Myc._, I., p. 6; t. III., Fig. 2.

1828. _Physarum sinuosum_ Wein., Fries _teste, l. c._ 1828. _Angioridium sinuosum_ Grev., _Scot. Crypt. Fl._, 310.

1829. _Physarum sinuosum_ Fries, _Syst. Myc._, III., p. 145.

1875. _Physarum sinuosum_ (Bull.) Rost., _Monograph_, p. 112.

1892. _Physarum sinuosum_ Rost., Ma.s.see, _Mon._, p. 305.

1894. _Physarum bivalve_ Pers., Lister, _Mycetozoa_, p. 57.

1896. _Angioridium sinuosum_ (Grev.), Morg., _Cin. Soc. Nat. Hist._, p. 75.

1899. _Physarum sinuosum_ (Bull.) Wein., Macbr., _N. A. S._, p. 28.

1911. _Physarum sinuosum_ Wein., Lister, _Mycetozoa, 2nd ed._, p. 76.