i. Stipe when present yellowish

+ Wall iridescent, spores uniformly marked 11. _B. utricularis_

++ More calcareous, spores strongly marked on one side 12. _B. capsulifera_

+++ Colorado, spores anon barred 13. _B. populina_

ii. Stipe when present black 14. _B. papaveracea_

_d._ Sporangia brown, lilacine

i. Sessile 15. _B. lilacina_

ii. Stipitate, columellate 16. _B. rubiginosa_

1. BADHAMIA OVISPORA _Racib._

1884. _Badhamia ovispora_ Racib., _Myx. Ag. Cracov._, XII., p. 72.

Sporangia sessile depressed-globose or plasmodiocarpous, white or ochraceous, covered by dense calcareous scales; capillitium white, the lime-granules sometimes aggregate at the center to form a pseudo-columella; spores not adhering, brownish-purple ellipsoidal, 8 x 10-10 x 15 mu.

Reported from Bohemia, England, Pennsylvania.

2. BADHAMIA VERSICOLOR _Lister_.

1901. _Badhamia versicolor_ List., _Jour. Bot._, XXXIX., p. 81. 1911. _Badhamia versicolor_ List., _Mycetozoa 2nd ed._, p. 35.

Sporangia scattered or clustered, minute, .3-.5 mm., grey or flesh-colored, sessile, the calcareous deposits slight; capillitium white or apricot-colored; spores ovoid, 8 x 10-9 x 12 mu, clustered, purplish, and warted at the broader end, elsewhere colorless and smooth.

This little species, as it comes to us, is grey, very uneven in size, .2-.5 mm. and generally irregular in form and habit, perhaps scarce mature. The capillitium is white, physaroid. The spores furnish the distinguishing character. Sometimes globose, about 9-10. They are most of them definitely and permanently affected in shape by the fact of cluster-association, narrower in the direction of the cluster center. The indications are that these may become globose with maturity.

Colorado,--_Bethel_; Scotland.

3. BADHAMIA DECIPIENS (_Curtis_) _Berk._

1848. _Physarum decipiens_ Curtis, _Am. Jour. Sci._, VI., p. 352. 1873. _Badhamia decipiens_ Berk., _Grev._, II., p. 66. 1873. _Physarum chrysotrichum_ Berk. & C., Grev. II., p. 66. 1876. _Badhamia chrysotricha_ (Berk. & C.) Rost., _App._, p. 4.

Sporangia gregarious, depressed-spherical or ovate, sessile, occasionally plasmodiocarpous, dull yellow, roughened by the rather large numerous calcareous scales; columella none; capillitium dull orange, strongly calcareous, only slightly widened at the nodes; spore-mass black; spores pale violet, minutely spinulose, free, 10-12 mu.

Among badhamias this and the next species are at once distinguished by the color. If the brief description (_Grev._, II., p. 66) can be regarded as defining anything, this is the same as _P. chrysotrichum_ Berk. & C. It resembles somewhat _P. serpula_ Morg., but differs externally in color and in the surface scales, which are not perceptible in the _Physarum_. The present species also resembles _Cienkowskia reticulata_ (Schw.) Rost., but has a different capillitium. See under that species.

Chiefly eastern and American. New England, Pennsylvania, Ohio, South Carolina; reported recently also from Sweden and Germany.

4. BADHAMIA NITENS Berk.

1852. _Badhamia nitens_ Berk., _Trans. Linn. Soc._, XXI., p. 153. 1863. _Badhamia inaurata_ Currey, _Trans. Linn. Soc._, XXIV., p. 156. 1873. _Badhamia nitens_ Berk., Rost., _Mon. App._, p. 3.

Sporangia gregarious or closely crowded, globose or depressed-globose, .5-1 mm. in diameter, yellow or greenish yellow, rugulose, sessile; capillitium yellow, forming an open net with occasional thickenings at the nodes; spores clustered, delicately roughened, violaceous-brown, 10-12 mu.

This much resembles the preceding species except in the clustered spores, and more commonly aggregate habit. The spores, as usual when clustered, are conspicuously echinulate on the outer side. This did not escape the notice of the author of the species, _op. cit._

Colorado, Oregon. Reported from West Indies, Ceylon, various parts of Europe.

5. BADHAMIA PANICEA (Fries) Rost.

1829. _Physarum paniceum_ Fries, _Syst. Myc._, III., p. 141. 1873. _Badhamia panicea_ (Fr.) Rost., Fuckel, _Sym. Myc. Nachtr._, 2, p. 71.

Sporangia gregarious or aggregated in closely compacted clusters, globose or hemispherical, sessile, the peridium thin, transparent, thickly dotted with white calcareous scales; stipe none; columella none, although a pseudo-columella sometimes appears, formed by a more dense development of the capillitium near the centre of the sporangium below; capillitium abundantly developed, quite uniformly thickened, but showing an occasional delicate connecting thread, the nodes also somewhat flattened and enlarged; spore-mass black; spores by transmitted light, bright violaceous-brown, minutely roughened, 10-13 mu. Plasmodium is said to be white.

In America this seems to be a purely western species. Specimens are before us from western Iowa and from Colorado, South Dakota, Nevada, and Southern California. It is very well marked, though liable perhaps to be mistaken at first sight for sessile phases of _P. notabile_ or _P. cinereum_. The capillitium is, however, at once determinative. Colorado; _Bethel_. Europe generally.

6. BADHAMIA AFFINIS _Rost._

1875. BADHAMIA AFFINIS Rost., _Mon._, p. 143.

Sporangia aggregated, cespitose and sessile, or sometimes stipitate, depressed above, flat or umbilicate below, the wall grayish white, rugulose, and more or less calcareous-scaly; the stipe when present erect or sometimes nodding, black or brownish black; hypothallus scanty; columella none; capillitium not abundant, white, the nodes somewhat expanded; spores globose, minutely roughened, violet-brown, large, 16-17 mu.

Chiefly on moss, the pale ashen sporangia generally very small, mounted on the tips of the leaves, sometimes sessile, sometimes with a distinct black stipe in which case the peridium is distinctly umbilicate. Specimens from Kansas referred here have the stipe pale, rugose, long, about twice the sporangium; habitat bark.

Rare. New York, Ohio, Kansas; more recently reported from Scotland and Japan.

There is nothing new to be added here; nor appears any other place to which such material as we have may be referred. New collections no doubt will one day appear, when the identity may, let us hope, be made secure.

Meantime we have a form closely related which may be entered as

BADHAMIA IOWENSIS _Macbr. n. s._

Sporangia gregarious or loosely scattered, depressed globose, .4-.6 mm. in diameter, stipitate, grey, flecked by rather prominent but small rounded calcareous scales: the stipe short, half the diameter of the sporangium, black or very dark brown, without hypothallus but widening above into a shallow expanded base for the sporangia; columella none: capillitium dull yellow, sometimes white, strongly calcareous, physaroid, heavy; spores free, dark brown in mass, pale violet by transmitted light, minutely verruculose, the tiny warts in some areas more densely placed, producing evident shadowy spots, 10-11 mu.

This interesting little species occurs on the lower surface of fallen logs, blocks, etc., in colonies of considerable extent, hundreds of sporangia in a place. The capillitium is comparable to that of _B. decipiens_ or _B. panicea_; it is physaroid to the extent that an occasional filament may be found non-calcic, and not typically badhamioid as in _B. papaveracea_, _B. macrocarpa_. The sporangial base persists, dark brown, bearing traces of the clumsy capillitium, but no columella real or simulated. Blackhawk Co., Iowa; _communicavit Dr. Jessie Parish_. See Plate XX., 1, 1 _a_, 1 _b_.

Reddish or roseate forms sometimes appear in colonies otherwise as described. It differs from _B. affinis_ in the size and character of the spores, in color and character of the capillitium, habit and surface markings.

7. BADHAMIA MACROCARPA (_Ces._) _Rost._

1855. _Physarum macrocarpon_ Cesati, _Flora_, XXXVIII., p. 271. 1875. _Badhamia macrocarpa_ (Ces.) Rost., _Mon._, p. 143.

Sporangia scattered or closely aggregate, crowded globose or sub-globose, generally sessile, rugulose, white; the peridium membranous, white above, below yellowish or brown; capillitium not abundant, thoroughly calcareous, the nodes broad, conspicuous, the connecting tubules rigid; columella none; hypothallus scant or none; spore-mass black, spores non-adherent, by transmitted light bright clear brown, thickly spinulose all over, large spherical, 12-15 mu.

Closely resembles externally _B. panicea_, but is easily distinguished by larger and remarkably _spinulose_ spores, in this particular unrivalled in the entire genus. European authors describe both sessile and stipitate forms. American specimens generally are sessile and for the most part closely crowded, almost heaped; but--Prof. Bethel finds this in winter everywhere on fallen rotting stems of Opuntia and on the bases of dead Yucca leaves, still attached. Associated with the typical phase and often _occurring alone on the Yucca_ leaves is a discoidal form which when first sent in (1908) was called var. _gracilis_. Presented alone to one ignorant of its history and associations, it would surely pass for a distinct species. This stalked phase is very delicate; the stipe pale brown, or yellow. See Plate II., Fig. 9. See also Sturgis _Col. Coll. Pub._ XII., 408.

8. BADHAMIA ORBICULATA _Rex._

PLATE XIV., Fig. 4.

1893. _Badhamia orbiculata_ Rex. _Proc. Phil. Acad._, p. 372. 1894. _Badhamia macrocarpa Rost._, Lister, _Mycetozoa_, p. 34 (in part). 1911. _Badhamia orbiculata_ Rex., Lister, _Mycetozoa, 2nd ed._, p. 37

Sporangia stipitate or sessile, orbicular discoidal, irregularly elongated or plasmodiocarpous, averaging about 1 mm. in width, generally stipitate, and when stipitate, flattened or depressed above, plane or slightly umbilicate below; the peridium simple, more or less translucent from the varying number of innate granules, sometimes covered with circular flat masses of lime, gray except the point of attachment to the stipe which is brown; stipe short, black, rough, plicate; capillitium dense at the centre, radiant at the periphery where it meets the sporangial wall, white; spores violaceous black, minutely warted, 12-15 mu.

This is a beautiful species, easily known by its discoidal or almost annulate sporangia mounted upon short dark black stipes. The stipe in western collections is sometimes very short, but generally suffices to raise the sporangium, a little at least, above the substratum. Sessile and plasmodiocarpous forms do occur with the typical stipitate phase, but may be regarded here as elsewhere as indicative of incomplete development. Plasmodium cream-colored, or pale yellow.

Pennsylvania, Ohio, Iowa, Nebraska, South Dakota, Colorado.

9. BADHAMIA MAGNA _Peck._

PLATE XIV., Fig. 1.

1871. _Dictydium magnum_ Peck, _Rep. N. Y. State Mus._, XXIV., p. 84. 1879. _Badhamia magna_ Peck, _Rep. N. Y. State Mus._, XXXI., p. 56. 1894. _Badhamia macrocarpa Rost._, Lister, _Mycetozoa_, p. 34, in part. 1892. _Bahamia varia_ Mass. _Mon. Myxog._, p. 319, in part. 1894. _Badhamia magna_ Peck, List., _Mycetozoa_, p. 33. 1899. _Badhamia capsulifera_ (Berk.) Macbr., _N. A. S._, p. 68. 1911. _Badhamia magna_ Peck, Lister, _Mycetozoa, 2nd ed._, p. 34.

Sporangia globose or ellipsoid, .7-1 mm., pale iridescent, stipitate; peridium thin with slight calcareous deposits, rugulose, opening irregularly, white; stipe long flaccid, straw-colored; capillitium an elegant uniform net, its threads stiffened by slight deposits of lime, the nodes little thickened, badhamioid; spores free, dusky with a shade of violet, minutely spinulose, about 10 mu.

This beautiful species closely resembles some forms of _B. utricularis_ from which it differs chiefly in its unclustered smooth spores. _B. foliicola_ as recognized here is hardly more than a smaller, short-stemmed form of this; see species next following.

Not rare in the eastern United States and Canada; Iowa. Seems to take the place of _B. capsulifera_ of Europe.

10. BADHAMIA FOLIICOLA _Lister_.

1897. _Badhamia foliicola_ List., _Jour. Bot._, XXXV., p. 209. 1911. _Badhamia foliicola_ List., _Mycetozoa, 2nd ed._, p. 34.

"Plasmodium orange." Sporangia smaller, about .5-.6 mm., globose or ellipsoidal, iridescent-gray, stipitate or sessile, the peridium thin, rugulose, sparingly calcareous, when empty white; the stipe when present short but yellowish, of the flaccid sort; capillitium badhamioid; spores free, delicately spinulescent, dusky-violaceous, about 12-13 mu.

This has been so far collected but once, on the shores of Lake Okoboji. It was developed, no doubt, on the natural debris of a bur-oak prairie border, and went to fruit on the leaves, stems, and fruiting spikes of a species of _Setaria_. It may prove to be different from the _B. foliicola_ of Europe; future collections and study must reveal that. Meantime it seems wise to refer it here.

The color of the plasmodium is quoted from Miss Lister; a fact of some importance only when constant and confirmed by other criteria.

Iowa; Toronto,--_Miss Currie._

11. BADHAMIA UTRICULARIS (_Bull._) _Berk._

1791. _Sphaerocarpus utricularis_ Bull., _Champ._, p. 128, t. 417, Fig. 1. 1826. _Physarum utriculare_ Chev., _Fl. Paris_, I., p. 337. 1829. _Physarum utriculare_ Fries, _Syst. Myc._, III., p. 139. 1852. _Badhamia utricularis_ (Bull.) Berk., _Tr. Linn. Soc._, XXI., p. 153.

Sporangia clustered, spherical or ovoid, large, sessile or mounted on long, thin, strand-like stalks, blue-gray, violet-iridescent or cinereous, smooth or more often rugulose; the stipes when present poorly differentiated, as if thread-like filaments and strips of the plasmodium, often branched and always reclining or even prostrate; hypothallus none; capillitium a large-meshed open network of rather slender tubules, the nodes unequally developed, white with the enclosed lime; spores not strictly adherent though not without some tendency to stick together, delicately warted, bright violet-brown, 10-12 mu.

This species resembles _B. capsulifera_, but is distinguished by a more strongly rugulose less calcareous peridium and a more profuse development of filamentous stipes, but especially by the character of the spores. The spores of the present species while inclined, when mounted in a liquid, to stay together, nevertheless do not coalesce in heaps as in the related species, nor do they show any differentiation in the episporic markings, these being uniform over the entire spore.

This is one of the finest and perhaps the most beautiful species of this fine genus. It is a forest species, generally to be found on trunks of fallen _Populus_ or _Tilia_ where the fine soft gray colonies often spread for several inches along the ridges and in crevices of the bark.

Colorado (_Bethel_); Mississippi valley and east.

12. BADHAMIA CAPSULIFERA (_Bull._) _Berkeley_.

1791. _Sphaerocarpus capsulifer_ Bull., _Champ._, p. 139, t. 470, Fig. 2. 1801. _Physarum hyalinum_ Pers., _Syn. Meth. Fung._, p. 170. 1852. _Badhamia capsulifera_ Berk., _Tr. Lin. Soc._, XXI., p. 153. 1852. _Badhamia hyalina_ Berk., _Tr. Lin. Soc._, XXI., p. 153. 1875. _Badhamia hyalina_ (Pers.) Rost., _Mon._, p. 139. 1875. _Badhamia capsulifera_ (Bull.) Rost., _Mon._, p. 141. 1894. _Badhamia hyalina_ Lister, _Mycetozoa_, p. 30. 1911. _Badhamia capsulifera_ Lister, _Mycetozoa, 2nd ed._, p. 31.

Sporangia clustered or gregarious, sessile or sometimes stipitate, globose or obovoid, gray or greenish white, snow-white when empty; the peridium thin, translucent; the stipe, when present, as in _B. utricularis_, although generally shorter and better developed, yellow or straw colored; capillitium a very loose, open network of white, lime-filled tubules, not much expanded at the nodes; columella none; spore-mass purplish-brown; spores adhering in clusters of five or six to twenty or more, globose, but affected somewhat by mutual pressure, rough throughout, the exposed surface in the cluster, more distinctly warted, 10-12 mu.

This is _Badhamia hyalina_ (Pers.) Berk., Rost., _Mon._, p. 139; but Rostafinski himself admits that the two species, here united, as he defined them, are very much alike, having "the same spores and capillitium", differing in the form of the sporangium, an inconstant feature. Bulliard's name has precedence; his descriptions of this and the preceding species are remarkable.

The peculiarly adherent spores distinguish the species from _B. utricularis_; and the sporangia sessile or with short but strand-like stipes, distinguish it from _B. papaveracea_.

The description above is for the typical European form. Lister expresses doubt whether this occurs in the United States. The form from Iowa which is the basis for the inclusion of the species in N. A. S. is, we believe, nothing else than _B. capsulifera_ (Bull.) Berk. The form approaches _B. populina_ as this is presented in Colorado. The Iowa specimens are white, aggregate, superimposed, etc., but have the capillitium and spores exactly as described for the type. Accordingly _B. populina_ as this occurs in Colorado has been for years referred to the Berkeley species. The thicker more strongly calcareous peridia constitute, as would appear, the principal difference in the forms from Colorado. See next species.

13. BADHAMIA POPULINA _List._

1904. _Badhamia populina_ List. _Jour. Bot._, XLII., p. 129. 1911. _Badhamia populina_ List. _Mycetozoa, 2nd ed._, p. 32.

Plasmodium white; sporangia sessile, crowded, heaped, large, 1.5 mm., rarely stipitate, globose or ovoid, white; stipe when present brown; capillitial strands broad, calcareous; spores clustered, 16-20 in a cluster, purple-brown, roughened and sometimes marked by obscure ridges and bands, 10-12 mu.

Generally distinguishable by its unusually large calcareous, white sporangia. The peridia are strongly calcareous, shell-like in texture. In some cases the color is tinted with rose.

This species is very near _B. capsulifera_ as recognized in the United States. When white the Colorado material corresponds almost exactly with the forms collected in Iowa, and regarded as representing the species just named. The Colorado gatherings are more strongly calcareous and the spores sometimes present the variations named. "The Colorado phase of the American form."

Colorado,--_Bethel_. Europe?

14. BADHAMIA PAPAVERACEA _Berk. & Rav._

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

1873. _Badhamia papaveracea_ Berk. & Rav., _Grev._, II., p. 66. 1894. _Badhamia hyalina_ var. _papaveracea_ Lister, _Mycetozoa_, p. 30. 1899. _Badhamia papaveracea_ Berk. & Rav., Macbr., _N. A. S._, p. 69. 1911. _Badhamia papaveracea_ Berk. & Rav., List., _Mycetozoa, 2nd ed._, p. 32.

Sporangia gregarious, globose, large, stipitate, iridescent-gray; the peridium thin, translucent, and containing but little calcareous deposits, smooth or slightly rugulose; stipe very short, but generally distinct, black or very dark brown; hypothallus none; capillitium a network of large meshes with expanded nodes, prominent, white, persistent after the spores have been blown away; spore-mass deep brown; spores adherent as in _B. capsulifera_, marked in much the same way, and about the same size, 10-12.5 mu

Distinguished by its short, dark, stipe and adherent spores.

Not common. New England, Pennsylvania, Ohio, Maryland, South Carolina, Wisconsin, Iowa.

15. BADHAMIA LILACINA (_Fries_) _Rost._

1829. _Physarum lilacinum_ Fries, _Syst. Myc._, III., p. 141. 1875. _Badhamia lilacina_ (Fries) Rost., _Mon._, p. 145. 1892. _Craterium lilacinum_ Mass., _Mon._, p. 271. 1894. _Badhamia lilacina_ (Fr.) Rost., Lister, _Mycetozoa_, p. 34. 1911. _Badhamia lilacina_ (Fr.) Rost., List., _Mycetozoa_, 2nd ed., p. 38.

Sporangia globose, sub-globose, or obconical, sessile, gregarious or more or less clustered, supported by a thin, continuous, transparent hypothallus; the peridium smooth pale, lilac-brown without, white within; stipe none, although some sporangia have a narrowed base; columella none, the pseudo-columella formed by a more densely aggregated capillitium near the base; capillitium dense, white, strongly nodulose; spore-mass black; spores dark, violaceous-brown by transmitted light, distinctly warted, or reticulate, the reticulations resembling somewhat those of some of the trichias, as _T. affinis_, 10-15 mu.

Easily recognizable, generally at sight, by its peculiar color. White forms, however, occur; often lilac-tinted and white from the same plasmodium. A perfectly white colony seems to be rare. Both colors are shown in specimens distributed. _N. A. F._, 2494.

Common eastward, Ontario, New England, Pennsylvania, Ohio, etc. Not reported west of the Mississippi River.

Whatever the color, the spores are in every case positively diagnostic. The episporic markings are unlike those of any other species in the present order. Dr. Rex describes some New York forms as provided with a short but distinct stipe. Such forms resemble externally _Scyphium rubiginosum_ (Chev.) Rost. The hypothallus is also unique. V. next species.

16. BADHAMIA RUBIGINOSA (_Chev._) _Rost._

PLATE X., Figs. 1, 1_a_, 1_b_, 1_c_.

1826. _Physarum rubiginosum_ Chev., _Fl. Par._, p. 338. 1872. _Craterium obovatum_ Peck, _Rep. N. Y. Mus._, XXVI., p. 75. 1875. _Scyphium rubiginosum_ (Chev.) Rost., _Mon._, p. 148. 1876. _Badhamia rubiginosa_ (Chev.) Rost., _Mon. App._, p. 5. 1892. _Craterium rubiginosum_ Massee, _Mon._, p. 270.

Sporangia gregarious, obovoid, grayish brown, stipitate, the peridium simple, membranous, above thin, pale, more or less calcareous below, more persistent blending with the stipe; stipe erect, reddish brown or purplish, expanded below into a small hypothallus, above, prolonged within the sporangia more than half its height as a definite columella; capillitium very dense, snow white, long persistent with the lower two-thirds of the sporangial wall; spore-mass dark brown; spores by transmitted light, dark violet or purple-brown, minutely roughened or spinulose, not adherent, 12-14 mu.

This is probably the most common badhamia in the country and in the world. It is found every year, in the woods, on masses of decaying leaves, especially those of various species of oak. The plasmodium is yellow. The fructifications are very distinct, not likely to be mistaken for those of any other species; the stipes constitute a very prominent feature in every gathering I have seen. Sometimes these are more or less coalescent, especially toward the base, where they are apt to be also wrinkled or longitudinally striate; in other specimens the stipes are well differentiated, long, terete, with little or no hypothallus.

_Badhamia curtisii_ (Berk.) Rost. is according to Lister (Mon., p. 35) a sessile phase of this species. The only specimens known are in the herbarium of Berkeley, now at Kew. The species is based upon a gathering from S. Carolina. Berkeley thought it a didymium, called it _D. curtisii_.

Reported from western Europe; the typical form abundant in the forested regions of eastern N. America, especially in the Mississippi valley.

17. BADHAMIA SUBAQUILA _Macbr._

1899. _Badhamia subaquila_ Macbr., _N. A. S._, p. 64.

Sporangia closely gregarious or crowded, globose or sub-globose, sessile, brown, the peridium a thin but persistent brown membrane, rupturing above irregularly and remaining as a cup after spore dispersal; hypothallus none; capillitium strongly developed, thoroughly calcareous, the meshes large, the nodular thickenings broad, white; spores globose, in mass black, by transmitted light brown, very rough-warted, large, 15-18 mu.

The variety is founded on material sent from Maine by the late Mr. F. L. Harvey. Professor Harvey, upon the authority of Mr. Morgan of Ohio, quotes the species, _Bull. Tor. Bot. Club_, 24, 67, as _B. verna_ (Somm.) Rost. But the specimens certainly do not conform to description of _B. verna_. Here the wall corresponds with what is seen in _B. rubiginosa_; but the spores are much larger, and the capillitial structure very different.

Miss Lister regards this a form of No. 16. So far, the original gathering represents the species; but the woods of Maine are certain one day to send added information.

Rare. On mossy logs, Maine.

=3. Physarum= (_Persoon_) _Rost._

1794.[19] _Physarum_ Pers., _Rom. Neu. Mag. f. d. Bot._, I., p. 88, in part. 1795. _Physarum_ Pers., _Ust. Ann. Bot._, XV., p. 5, in part. 1801. _Physarum_ Pers., _Syn. Fung._, p. 168, in part. 1829. _Physarum_ (Pers.) Fries, _Syst. Myc._, II., p. 127, in part. 1875. _Physarum_ (Pers.) Rost., _Mon._, p. 93.

Sporangia plasmodiocarpous, aethalioid or distinct; the peridium usually simple, sometimes double, irregularly dehiscent, more or less definitely calcareous; capillitium a uniform irregular net, dilated and calcareous at the nodes, adherent on all sides to the peridial wall.

This large and cosmopolitan genus is readily recognized by the characters quoted. It may be added that the capillitial threads are always exceedingly delicate, probably tubular, but never filled with lime throughout; the peridium may be almost nude or encrusted with lime, which, where present, is always amorphous, never crystalline; the sporangia when distinct may be either sessile or stipitate, and the stipe in the latter case is often hollow and charged with lime. In capillitium intermediate between _Leocarpus_ and _Badhamia_, since in the first the capillitium is unequally calcareous, diverse, while in _Badhamia_ the capillitium is intricate and calcareous throughout.

As first set up by its founder, the genus included diverse forms, only one or two of which would be included in the genus as now limited.[20] Persoon, however, was left to develop the matter to suit himself, and in successive works gave, under this generic name, more and more prominence to forms now so referred. Fries, _Syst. Myc._, III., pp. 127 _et seq._, still better establishes the genus, though still including forms that, judging from the description, seem to belong elsewhere. Twenty years later Fries revising somewhat his earlier work thought to improve the chances of future students by reducing the number of physarums. This he would do by setting out certain evidently inter-related forms to make a new genus, _Tilmadoche_.

He named two or three species only, leaving his sucessors to add others as occasion offered.[21]

Rostafinski approved the good intention of Fries, but in the _Monograph_, he entirely re-cast the genus as constituted by Fries; actually called the species 'first cited' a typical physarum! Would not have it in the new genus at all, first or last; but instead took the second species of Fries as the type and added several forms, some from the Friesian list, to make up a respectable group.

Until quite recently writers on the subject have generally approved the course adopted by the Polish author. The arrangement showed features of convenience, even if artificial to a degree. Perhaps we gain advantage in all directions if we treat the original genus _Physarum_ as a whole, but in the key take advantage of Fries' suggestion. We may write--

=Key to the Species of Physarum=

1. Capillitium irregularly reticulate throughout; calcic nodes various _Physarum_

2. Capillitium more regular, especially below, furcate; nodes fusoid _Tilmadoche_

SECTION I. PHYSARUM

I. Fructification not stipitate, more or less plasmodiocarpous.

1. Peridium simple.

_a._ Calcareous deposits yellow 1. _P. serpula_

_b._ Calcareous deposits reddish or orange 2. _P. lateritium_

_c._ Calcareous deposits white, peridium rugulose 3. _P. vernum_

2. Peridium double.

_a._ Fructification flatly compressed 4. _P. sinuosum_

_b._ Fructification less compressed, rounded.

i. Outer peridium white 5. _P. bitectum_

ii. Outer peridium brown or brown-tinged 6. _P. bogoriense_

iii. Outer peridium yellow; capillitium yellow 7. _P. alpinum_

II. Fructification of sporangia more or less distinct.

A. Sporangia sessile, globose, ovoid, reniform, etc.

1. Peridium double.

_a._ Sporangia white, peridium testaceous. 8. _P. diderma_

_b._ Sporangia tinged with yellow.