In the Kew Herbarium, it is said, are two American specimens under one label, "Didymium pusillum." One specimen is a didymium indeed, but, as it appears, D. proximum Berk., already described. The other is a physarum. It is proposed in Mycetozoa, 2nd ed., to use the combination thus set free, as if applied by the original author to the second specimen, not didymium, and to make the new combination date from 1873 and so take precedence of the binomial applied in 1881 by Cooke and Balfour here retained by the law of priority.

35. PHYSARUM MACULATUM Macbr.

PLATE XIV., Figs. 6, 6 a, 6 b.

1893. Bull. Lab. Nat. Hist. Iowa, II., p. 383. 1899. Physarum maculatum Macbr., N. A. S., p. 47. 1911. Physarum tenerum Rex., Lister, Mycetozoa, p. 52, in part.

Sporangia scattered or gregarious, very small, .3-.4 mm., dull gray, thin-walled, dotted with minute, white calcareous granules, stipitate; stipe long, about 2 mm., stout, attenuated upward, striate longitudinally or wrinkled, filled with irregular yellow masses of lime and accordingly bright yellow in color; columella none; capillitium forming a dense net, with comparatively small yellow nodular thickenings; spores globose, purplish, each minutely papillose and displaying several scattered spots occasioned by local development of the papillae; diameter of the spores 9-10 mu.

This species was set up for the reception of certain material collected by Professor Shimek, in 1892, in Nicaragua. It remains so far unique. The small globose sporangium mounted upon a long upwardly tapering stipe, .5 mm. thick below, but narrowed at the extreme base where it is lightly attached, a stem which is simply a sack stuffed with yellow lime-granules;—this and the yellow capillitium are distinguishing features. The capillitium and spores suggest Tilmadoche viride, but the entire habit precludes such reference. Perhaps nearest to P. melleum.

Castillo, Nicaragua.

Miss Lister thinks this the same as P. tenerum Rex. But the whole habit and external appearance are different; the stipe notably long, clumsy, surcharged with lime; a very singular form.

36. PHYSARUM DIDERMOIDES (Pers.) Rost.

PLATE IX., Figs. 1, 1 a, 1 b, 1 c.

1801. Spumaria (?) didermoides Acharius, Pers., Syn. Fung., p. xxix. 1829. Diderma oblongum Fr., Syst. Myc., III., p. 103. 1831. Spumaria licheniformis Schw., N. A. F., p. 261, No. 2364. 1832. Physarum atrum Schw., Syn. Fung., Am. Bor., p. 258. 1875. Physarum lividum, Schw., Rostafinski, Mon., p. 96. 1875. Physarum didermoides (Ach.) Rost., Mon., p. 97.

Plasmodium pale, watery-white or gray; sporangia crowded, ovoid or cylindric, stipitate or sessile, blue-gray, often capped with white; stipe variable in length and structure, where well developed pure white, often flattened, expanded and diaphanous, connate with others through the irregular reticulate or sheet-like hypothallus; columella none; capillitium ample, the lime knots angular or rounded, white connected by hyaline threads; spores in mass black, by transmitted light dark violet, decidedly spinulose, 12-15 mu.

A very variable species in many particulars. The sporangia in the same cluster are stipitate and sessile, ovoid and spherical. Our description does not quite agree with that of Rostafinski. As may be seen from the plate, it is the outer peridium that is with us white, burdened with lime, the inner is simpler and comparatively thin. The whiteness of the outer peridium is however, easily displaced. The colony may not show it at all, in which case the peridia remaining give to the fructification entire a pale lead color, very characteristic. The disposition of the lime in the capillitium is also notably variable. Specimens occur which in so far realize Rostafinski's Crateriachea; that is, the lime is massed as a snow-white pseudo-columella in the centre of each sporangium. In such cases the lime of the outer peridium is scant or limited in amount, never forming the calcareous cap shown in Fig. 1. The size of the spores is also variable. Rostafinski gives 12.5-14.2 mu; not infrequently a single spore reaches 16 mu, a very unusual range of variation.

The species is not common in the upper Mississippi valley, but can be obtained in quantity where once it appears, as the plasmodia are profuse.

Ohio, Carolinas, Tennessee, Iowa, South Dakota, Kansas. Especially to be looked for on the bark of fallen stems of Populus and Negundo.

Brazil, India, Japan.

Physarum lividum Rost., Mon., p. 95, is but a less calcareous form of this, as is evident even by the author's description. Professor Morgan thought P. lividum a phase of P. griseum Lk. Link, however, reckons P. griseum the same as P. cinereum. Link, Diss., I., p. 27.

37. PHYSARUM LEUCOPUS Link.

PLATE IX., Figs. 7, 7 a, 7 b.

1809. Physarum leucopus Link, Diss., I, p. 27.

Sporangia gregarious, stipitate, globose snow-white, with a didymium like covering of calcareous particles; stipe white, not long, conical or tapering rapidly upward, slightly sulcate, brittle, from an evanescent hypothallus; columella none or small; capillitium, consisting of rather long hyaline threads, connecting the usual calcareous nodes, which are large, angular, snow-white; spore-mass black; spores by transmitted light, violet-brown, distinctly warted, about 10 mu.

The snow-white, nearly smooth stem, the small sporangium (1/2 mm.) covered with loose calcareous granules, distinguish this rare species. It looks like a small Didymium squamulosum. Fries called it D. leucopus, Syst. Myc., III., p. 121.

Rare. Iowa, Ohio, Maine; Portugal.

38. PHYSARUM COMPRESSUM Alb. & Schw.

PLATE XVIII., Fig. 14, and PLATE XIX., Fig. 12 and Fig. 4.

1805. Physarum compressum Alb. & Schw., Fung. Lus., p. 97. 1875. Physarum nefroideum Rost., Mon., p. 93, in part. 1875. Physarum affine Rost., Mon., p. 94. 1909. Physarum compressum Alb. & Schw., Torrend, Fl. des Myx., p. 197. 1911. Physarum compressum List., Mycetozoa, 2nd ed., p. 70.

Sporangia more or less scattered, compressed-globose, or compressed-reniform, i. e. often umbilicate, stipitate, sessile, or elongate as if plasmodiocarpous, calcareous, white or ashen; peridium thin, covered with squamules, opening irregularly, usually by apical cleft; stipe, when present, short, stout, more or less sulcate, dark brown or ashen; capillitium a rather loose net, the nodules white, variable in size and shape; spores purplish-brown, delicately roughened, about 10-12.5 mu.

P. affine R. was in this connection set up for European types compressed indeed, but more strongly reniform. The author says in his further description that the form affine is less definitely umbilicate, has white stems, etc.; allantoid, one would now say. Such forms now begin to appear in America; and if for these a specific name is needed, it is provided, P. affine Rost., Plate XIX., Fig. 4.

This seems to be a cosmopolitan species, now that we have found it. However, in North America it is rare. It is reported from Pennsylvania, from Colorado; Harkness found it in California, and the writer has often collected it in Oregon, on Mt. Rainier, Washington, and in California. Europe.

39. PHYSARUM NOTABILE nom. nov.

PLATE IX., Figs. 2, 2 a, 2 b; PLATE XV., Fig. 2; and Frontispiece.

1873. Didymium connatum Peck, Rep. N. Y. Mus., XXVI., p. 74. 1879. Physarum polymorphum (Mont.) Rost., Peck, Rep. N. Y. Mus., XXXI., p. 55. 1893. Physarum leucophaeum Fr., Ellis, N. A. F., No. 2396, second exhibit. 1893. Physarum leucophaeum Fries, Macbr., Bull. Lab. Nat. Hist. Iowa, II., p. 156. 1894. Physarum compressum Alb. & Schw., List., Mycetozoa, p. 53, in part. 1896. Physarum connexum Link., Morg., Jour. Cin. Soc., p. 92, in part. 1896. Physarum confluens Pers., Morg., l. c., p. 94. 1899. Physarum nefroideum Rost., Macbr., N. A. S., p. 41, in part. 1911. Physarum connatum Lister, Mycetozoa, 2nd ed., p. 71.

Sporangia gregarious, sessile, stipitate, or even plasmodiocarpous; when stipitate, depressed, varying at times to irregular reniform in the same colony; globose, the peridium strongly calcareous, cinereous-white; stipe variable, generally tapering upward, always distinctly deeply plicate-furrowed throughout, in color dark, opaque, sometimes touched with white or gray; capillitium abundant, the white lime-knots, varying in size and shape, connected by rather long hyaline threads, with here and there an empty node; spore-mass black, by transmitted light, dark, sooty brown, minutely papillose, 10-11.5 mu.

This remarkable species, while not at all difficult of recognition to one familiar with its phases, is withal very difficult to define. Normally stipitate, it often shows from the same plasmodium all sorts of forms, the shape of the fructification dependent apparently upon external conditions prevalent at the time. The amount of calcium also varies, especially in the capillitium, where there is usually much, with a tendency to the formation of something like a pseudo-columella; the outer net in such cases nearly destitute. The calcium in the stipe also varies; the black or brown stipes are, of course, free from it; the gray or white, calcareous.

In this large and difficult genus, since spore-color is receiving increased consideration,—see No. 31 preceding,—it is proper to note that in the present case two types appear, one with spore-color under the lens, as described, the other with spores violaceous with no trace of black; unshadowed.

The preceding description is based on material assembled during forty years. The form is easily discoverable by any collector throughout the entire valley of the Mississippi and eastward to Nova Scotia. For its naming, students in America have vainly waited the decision of those having access to mycologic types in Europe. It seems now certain that the species is extremely rare in the old world if there occurrent; never seen by any of the earlier taxonomists including Fries and Rostafinski; perhaps adventitious in these later years, although thus far no specimen from Europe has reached this table.[24] P. nefroideum of Strasburg herbarium turns out, after all, teste Lister, to be P. compressum Alb. & Schw., which accordingly shall now enjoy state and station of its own; our concern in European nomenclature, in the present instance, almost disappears, and we return to our synonymy from this side of the sea.

Mr. Lister would recur to Dr. Peck's Didymium connatum, which indeed represents the present species. In such disposition, how gladly would all concur, were the thing possible! But Physarum connatum is already a synonym twice over.[25] Unless we are done with the rules entirely, P. connatum cannot stand. P. polymorphum and P. leucophaeum are names already in use, of course; and so under the circumstances, much as it is to be regretted, there would seem nothing left to do but to cancel all past synonymy and impose a new name whose permanence may at least be hoped for, if not expected.

40. PHYSARUM TROPICALE Macbr.

1899. Physarum tropicale Macbr., N. A. S., p. 45.

PLATE XV., Figs. 4, 4 a, 4 b.

Sporangia scattered, gregarious, turbinate, short stipitate, blue-gray, about 1 mm. in diameter; peridium above iridescent, green, blue, etc., dotted with minute flecks of white, below limeless, purple or bronze shading to the brown of the stipe; stipe short, stout, slightly rugose, cylindric, non-calcareous, brown; columella none; hypothallus none; capillitium abundant, the nodes generally calcareous, small, uniform, angular, white, uniformly distributed; spore-mass, black; spores dark violet-brown, distinctly and closely warted, 12-15 mu.

A large handsome species recognizable by the peculiar turbinate sporangium, with its iridescent peridial wall in which green strongly predominates above, bronze below. The distinction between the upper and lower peridium would suggest Craterium, but the internal structure is not at all Craterium-like. The capillitium is typically of Physarum. The color suggests P. leucophaeum violascens Rost. From this species it is at once distinguished by its much longer sporangia, larger and rougher spores.

Mexico; C. L. Smith: Sure to be again collected once that unhappy country shall again open its forests to research.

41. PHYSARUM NICARAGUENSE Macbr.

PLATE XV., Figs. 7, 7 a, 7 b; XVII., 11 and 11 a.

1893. Physarum nicaraguense Macbr., Bull. Lab. Nat. Hist. Iowa, II., p. 383. 1894. Physarum compressum Alb. & Schw., List., Mycetozoa, p. 53, in part. 1910. Physarum nicaraguense Macbr., Petch, Mycetozoa Ceylon, p. 334. 1911. Physarum reniforme List., Mycetozoa, 2nd ed., p. 72, in part.

Sporangia multilobate or compound-contorted, below obconic, gray, ribbed with calcareous thickenings; stem short, fuscous, longitudinally wrinkled; hypothallus distinct, black; columella none, although the lime massed at the centre of each sporangium simulates one; capillitium white, densely calcareous, with heavy angular nodules connected with comparatively short threads; spores violet, globose, spinulose, about 12 mu in diameter.

Ometepe, Nicaragua. Professor B. Shimek.

This species resembles in some particulars No. 39, especially in the amount of lime present in both capillitium and peridium, in the fluted, sooty stipe, and the rough spores. Mr. Lister once regarded it as the same. Nevertheless, it differs from P. notabile in many definite particulars. In the first place, the sporangia are different in form and habit. They are obconic, nearly always compound, convolute, or botryoid, in this respect somewhat resembling P. polycephalum. Besides, the sporangia are uniformly much smaller, and show constantly the strongly calcified centre, much transcending anything seen in P. notabile. The stipe also is peculiar, quite short, an upward extension or sweep of the common hypothallus which is usually very distinct or prominent; and, while the stipe is longitudinally wrinkled, it is much less so than in the related species, and in a different way. The spores are about the same in size, but differ in color, in this respect agreeing rather with P. leucophaeum.

In the Mycetozoa, 2nd ed., l. c., the present species is entered as a synonym of two described by Massee: Tilmadoche reniformis Mass., Mon., p. 336, and Didymium echinosporum Mass., Mon. 239. But Massee's description of his tilmadoche is, naturally enough, at variance in every important point with the facts in the species before us. Massee says: "... sporangia deeply umbilicate below, sausage-shaped and curved; the stem elongated slender erect, pale brown; capillitial nodes scattered, fusiform, colorless or yellow; spores 16-17 mu." It is evident that whatever Massee may have had in hand as he wrote it was not P. nicaraguense, which has spores 10-12 mu and reverses the remaining description.

But Didymium echinosporum also defines T. reniformis since Lister, Mon., p. 54, says they are based on two gatherings of one species. Of this second species Massee says: "A superficial resemblance to T. nutans, but distinct in the capillitium which contains no trace of lime; spores 12-14 mu!" Again it is evident that whatever Massee had in hand when he wrote, it was not P. nicaraguense which "has capillitium almost Badhamia-like," i. e., burdened with lime!

Worse than all; Mr. Massee's alleged types are in evidence; one labelled P. reniforme[26] includes forms of P. didermoides and of P. nicaraguense; the other labelled by Berkeley P. nutans is P. nicaraguense. So Mr. T. Petch, Mycet. Ceyl., who enters our species as from Ceylon, and the names cited from Berkeley, Massee, and others, as synonyms. He remarks, "Probably Thwaites' 135 and 55 were mixed during examination"! Doubtless! and some other things too! What Massee did have beneath his lens, no one now may say but apparently not in either case cited, the physarum of Central America.

42. PHYSARUM SULPHUREUM Alb. & Schw.

1805. Physarum sulphureum Alb. & Schw., Consp. Fung., p. 93, Tab. VI, f. 1. 1818. Physarum flavum Fries, Symb. Gast., p. 22. 1875. Physarum sulphureum Alb. & Schw., Rost., Mon., p. 101.[27]

Sporangia gregarious, sub-globose, rugulose-squamulose, .6-.8 mm., sulphur-yellow, stipitate; peridium membranous, covered with calcareous scales; stipe stout, white, charged with lime, furrowed; columella none; capillitium strongly calcareous, the nodules large, white; spores violaceous, rough, 9-11 mu.

Northern Europe. (Lusatia) Lausitz, Alb. & Schw.; dim old Wendish region on the south borders of Brandenburg. Reported also from Sweden.

The description and figure given by Schweinitz, 1805, l. c., leave no doubt as to what he had in hand. Twenty or thirty years later, having spent the interval in this country,—bishop, indeed, of the Moravian churches, but a student of fungi all the while,—he reports the same thing from this country; Proc. Phil. Acad. Sci., 1834. Cooke also lists it in Myxomycetes of the U. S. It surely will be found again. Mr. Lister thinks P. variable Rex may be the same thing.

43. PHYSARUM CARNEUM G. Lister and Sturgis.

1910. Physarum carneum G. Lister and Sturgis, Jour. Bot., Vol. XLVIII, p. 63.

Sporangia gregarious, stipitate, sub-globose, .5 mm. in diameter, ochraceous-yellow above, flesh-colored below; peridium membranous, pale yellow, lime-granules evenly distributed; stipe short, translucent, pinkish flesh-colored; capillitium dense, nodules white; spores purplish-brown, spinulose, 8 mu.

Differs from P. citrinellum in the membranous peridium, flesh-colored stalks and smaller spores.

Colorado; Dr. W. C. Sturgis.

44. PHYSARUM CITRINELLUM Peck.

1831. Physarum caespitosum Schw., Syn. N. A. F., No. 2301 (?). 1869. Diderma citrinum Peck, Rep. N. Y. Mus., XXII., p. 89. 1870. Physarum citrinellum Peck, Rep. N. Y. Mus., XXXI., p. 55. 1894. Craterium citrinellum List., Mycetozoa, p. 74. 1899. Physarum caespitosum Schw., Macbr., N. A. S., p. 37. 1911. Physarum citrinellum Peck, List., Mycetozoa, 2nd ed., p. 62.

Sporangia gregarious, or scattered globose, short-stipitate, pale yellow or ochraceous, smooth or slightly roughened by the presence of minute lime-particles; peridium more or less distinctly double, the outer calcareous, fragile, the inner very delicate, with here and there a calcareous thickening, ruptured irregularly; stipe very short, half the sporangium, fuliginous, furrowed, expanded below into an imperfectly defined hypothallus; capillitium abundant, the nodes stellate-angular, large, the internodes delicate, short; spore-mass black, spores violaceous-brown by transmitted light, strongly spinulose, 10-12.5 mu.

A very distinct and handsome species. Easily recognizable at sight by its large, globose, almost sessile and yet distinctly stalked sporangia. The color to the naked eye is pale ochraceous or buff. Only under a moderate magnification do the citrine tints come out.

In the Twenty-second N. Y. Report, Dr. Peck incorrectly referred this species to Physarum citrinum Schum. On the appearance of Rostafinski's Monograph, Dr. Peck in his revised list, l. c., writes P. citrinellum Peck, with description on p. 57, following. Under the last name the species has been generally recognized in the United States and distributed. N. A. F., 2490.

In the former edition, this species was referred to P. caespitosum Schw., of which the original description is as follows: "P. caespitosum L. v. S., pulcherrimum. In foliis et stipitibus Rhododendri, Bethlehem. Physarum substipitatum aut saltem basi attenuata, caespitosim crescens et sparsim. Caespitulis 3 linearibus; peridiis stipatis, turbinatis, ovatis, basi contracta membranula exterori luteosquamulosa aut punctato-squarrulosa. Sporidiis nigro-brunneis, floccis citrinis inspersis." Synopsis N. A. Fungi, 2301.

The type from the Schweinitz herbarium is no longer in evidence. Without it, the reference cannot be sustained.

Not uncommon in the eastern United States; reported also from Japan.

45. PHYSARUM ALBESCENS Ellis.

PLATE XVI., Figs. 4, 4 a.

1889. Physarum albescens Ellis in litt: not described. 1893. Physarum auriscalpium Cke., Macbr., Bull. Lab. N. H. Iowa, No. 2, p. 155, in part. 1894. Physarum virescens var. nitens List., Mycetozoa, p. 59, in part. 1899. Physarum virescens var. nitens List., Macbr., N. A. S., p. 34, in part. 1899. Leocarpus fulvus Macbr., N. A. S., p. 82. 1911. Physarum fulvum Lister, Mycet., 2nd ed., p. 60. 1911. Physarum virescens, nitens List., Mycet., 2nd ed., p. 84, in part.

Sporangia gregarious, scattered, ovoid or globose, pale yellowish or fulvous, opening irregularly above, stipitate; the peridium double, the outer layer more or less calcareous, the inner delicate, almost indistinguishable, persistent below as a shallow cup; the stipe long, weak, striate, fulvous or yellow; hypothallus distinct, venulose, or more or less continuous; capillitium pallid or white, dense, with here and there below large continuous yellow calcareous nodules; columella none; spore-mass black; spores by transmitted light, dark brown, rough, 13-15 mu. Varies to forms with single (inner) peridium and simple physaroid capillitium. Vid. descriptions cited for P. auriscalpium, P. nitens, etc.

This interesting form is from our western mountains, and suggests at first a diderma; but the capillitium is entirely unlike that of a diderma in color and structure, and plainly belongs here. Plasmodium yellow, on fallen leaves and twigs. Our material is from Prof. Bethel, Denver; and Lake Tahoe, Nevada; later from Dr. Weir, Montana. No doubt common at high altitudes near the snow-line in mountainous regions, probably around the world.

As indicated above, this was originally entered as of the genus Leocarpus; the taxonomic history of the form may interest readers who note with surprise the presentation in synonymy here developed.

About thirty-five or forty years ago Dr. Harkness of California sent to Mr. Ellis of New Jersey a slime-mould which the sender referred to Diderma albescens Phillips, (Grev. V., p. 114, 1877). Ellis sent a small bit to the Iowa herbarium without other comment, save that he thought it a physarum. Sometime later Mr. Ellis received from Father Langlois, a correspondent in Louisiana, specimens he esteemed the same thing. He expressed the opinion that if this were what Phillips had found in California, it should perhaps be called a physarum. The Louisiana material by his courtesy came also to this table. The material was scanty, in poor condition, and all waited further light. To these specimens the writer paid less attention. They were in the hands of his correspondents and the courtesy of the case required their further consideration by Dr. Rex.

In 1889 Mr. Holway found in Iowa, a physarum of which he sent part to Ellis and the remainder to the writer who, then engaged on the Myxomycetes of East. Iowa, referred his part of this Iowa gathering to the Physarum auriscalpium Cke. as found in New York. Under this caption a specimen was later sent to Mr. Lister, who has, as we see, consistently regarded the thing as a variety of P. virescens Ditmar, P. nitens List.

Meantime in 1898 Colorado material from Professor Bethel reached the University. This did not recall any of the materials sent from Ellis. Diderma albescens had meanwhile come again from California, and been recognized as Diderma niveum Rost.

Accordingly, in N. A. S. the latest arrival from Colorado was described as a new species, and with some temerity perhaps, offered as a second species of the hitherto monotypic Leocarpus, all on account of the peculiar capillitium. Sometime after publication our most valued correspondent Mr. Bilgram called attention to the resemblance between the Colorado and Louisiana material already referred to. The University specimens as stated were small, broken, and in every way poor, but enough remained to indicate the evident justice of our correspondent's suspicion. Further investigation of the Holway material in Philadelphia showed that it too was entitled to consideration! Inasmuch as the Holway sending was all from one plasmodium, all difficulties vanished at once. The Iowa gathering showed two phases: one at the University represents P. nitens, physaroid, single-walled; while the Philadelphia part of the gathering corresponds, poorly it is true, but in fact, as now appears, to the form coming in perfection from Colorado; leocarpine in structure, published as Leocarpus fulvus; P. fulvum Lister. Since the combination P. fulvum is already in use, synonym of P. rubiginosum, it seems better to write the name suggested by Ellis; Physarum albescens never having been published, because Diderma albescens, as noted took care of itself.

Since Rostafinski we separate all these physaroid forms chiefly by capillitial characters: capillitial structure separates genera. Physarum diderma is a physarum despite its double wall. And so here Leocarpus was set out by its differentiating capillitium. In good specimens of the present species a large part of the capillitial net is entirely free from lime, so that when the peridium first opens at the summit, sometimes no trace of lime appears; the calcareous deposits are below, and tend to occupy not the nodal intersections as in Physarum, but in large masses involve portions of the net itself, nodes and all, as in Leocarpus. Miss Lister's beautiful figures, op. cit., Figs. 66 and 82, show this very well.

In The Journal of Botany, 52, p. 100, the distinguished author and artist records the discovery of this species in the mountains of Switzerland. She says: "This specimen shows a striking resemblance to Leocarpus fragilis Rost., both in the shape of the sporangia and in the capillitium and spores; but although the color of the sporangia varies in both these species, the walls of P. (L.) fulvum are membranous and rugose with included deposits of lime granules and show nothing of the polished cartilaginous layers characteristic of L. fragilis."

The species is a boundary type at best, and shows again how artificial all our taxonomy is apt to prove, when the number of presentations of some particular type becomes larger.

For these reasons, the present author writes Physarum, and believes the question of identity in a perplexing case fortunately settled.

46. PHYSARUM VARIABILE Rex.

1893. Physarum variabile Rex, Proc. Phil. Acad., p. 371. 1911. Physarum variabile Rex, List., Mycetozoa, 2nd ed., p. 47.

Sporangia scattered, stipitate, sub-stipitate or sessile, about 1 mm. high; regularly or irregularly globose, ellipsoidal, obovate or cylindric-clavate in shape; sporangium wall sometimes apparently thick, of a dingy yellow or brownish-ochre color, slightly rugulose on the surface, crustaceous, brittle, rupturing irregularly, sometimes thin, translucent, covered externally with flat circular calcic-masses falling away in patches; stipes nearly equal, occasionally much expanded at the base, rough, longitudinally rugose, variable in size, sometimes one-third of a millimetre high, sometimes a mere plasmodic thickening of the base of the sporangium; color of stipes varying from a yellowish-white to a dull brownish-gray; capillitium a small-meshed network of delicate colorless tubules with large, many-angled, rounded masses of white, or rarely yellowish-white lime-granules at the nodes; no true columella, but often a central irregular mass of white lime-granules; spores dark violet-brown, verruculose, 9-10 mu.

Pennsylvania. Dr. Rex.

Lister, op. cit., describes a variety, sessile, presenting plasmodiocarpous fructification, from Ceylon, also from Antigua, but there are some doubts as to the identity of these with American sessile and plasmodiocarpous forms. Vid. Jour. Bot. XXXVI., p. 113.

47. PHYSARUM AURISCALPIUM Cooke.

1877. Physarum auriscalpium Cooke, Myx. U. S., Am. Lyc. Nat. Hist. N. Y., XI., p. 384. 1877. Physarum auriscalpium Cke., Myx. Gr. Brit., Pl. 24, f. 253-4. 1893. Physarum sulphureum (Alb. & Schw.), Sturgis, Bot. Gaz., XVIII., p. 197. 1898. Physarum auriscalpium Cke., List., Jour. Bot., XXXVI., p. 115. 1911. Physarum auriscalpium Cke., List., Mycetozoa, 2nd ed., Syn. excl.

Sporangia scattered, stipitate or occasionally sub-sessile spherical, .8-1 mm. high; peridium granulated, bright golden yellow; stipe, when present, one-half to two-thirds the height of the sporangium, blackish-brown; hypothallus, minute, thin, brown; columella absent; capillitium rather dense, composed of large angular nodes, completely filled with bright yellow granules of lime, and connected by very short, delicate, colorless internodes destitute of lime; spores globose minutely verruculose, or asperate, 10.7-11.8 mu in diameter, brownish-violet by transmitted light, black in the mass.

This is the original description, 1893, of P. sulphureum (Alb. & Schw.) Sturgis; the author last named having compared certain stalked New England forms with what he could find of P. sulphureum in the herbarium of Schweinitz at Philadelphia, and having, as he thought, established identity.

Meantime Mr. Lister had been inclined to refer P. auriscalpium Cke. to P. rubiginosum Fr., Mycetozoa, p. 61.

In 1898 Professor Sturgis and Mr. Lister agreed that the New England specimens, owing to color and character of stipe and some other differences could not be the Schweinitzian species, but did indeed conform much better with those in London labelled P. auriscalpium Cke.

Accordingly P. sulphureum is something else, very different, (v. A. & S., Cons. Fung. Tab., VI., f. 1), and by aid of recent[28] discoveries in Sweden goes its own way again. Meanwhile P. sulphureum Sturgis stands, a new type for P. auriscalpium Cke., the description modified to suit; the lamented pioneer-author receives honor due, and his handsome species, with its "golden graving," may now march, let us hope, under appropriate banner far down the fair highway to future fame!

48. PHYSARUM OBLATUM Macbr.

PLATE III., Fig. 6; PLATE XIV., Figs. 3, 3 a, 3 b.

1879. Physarum ornatum Peck, Rep. N. Y. Museum, XXXI., p. 40 (?). 1893. Physarum oblatum Macbr., Bull. Lab. Nat. Hist. Iowa, II., p. 384. 1896. Craterium maydis Morg., Myx. Miam. Vall., p. 87. 1909. Physarum maydis Torr., Flor. des Myxo., p. 193. 1911. Physarum maydis Torr. List., Mycet., 2nd ed., p. 59.

Sporangia gregarious, stipitate, small, bright yellow, globose or depressed-globose, rough; stipe reddish-brown or fuliginous, even, short, slender; hypothallus scant, black, or none; columella none; threads of the capillitium yellow, delicate, connecting the rather dense and abundant yellow lime-granules; spore-mass brownish-black, spores violaceous, minutely but distinctly spinulose, 9-11 mu.

This species is easily recognizable by its brilliant yellow color, somewhat rugose, sometimes scaly peridium, its richly calcareous capillitium, also bright yellow where not weathered or faded, its dark brown, translucent, non-calcareous stem. In dehiscence, the base of the peridium in cup-form, sometimes persists. This circumstance, with the fact that decaying maize-stalks and leaves are a favorite habitat, led Professor Morgan to its description as Craterium maydis. But it is doubtless a physarum, occurring on habitats of all sorts, from Ohio to Iowa, Colorado and Washington. Ceylon(?).

Physarum ornatum Peck is doubtfully cited here, although Professor Morgan thought it the same as P. oblatum. As a matter of fact the original brief description, op. cit., does not suggest either P. oblatum or P. maydis; rather a form of Tilmadoche viridis. Professor Sturgis, Notes on Some Type Specimens of Myxo., in the N. Y. Museum, Trans. Conn. Acad. Arts and Sci., Vol. X., Pt. 2, p. 470, says that of the type almost nothing remains, that the name P. ornatum Pk. "should be discarded."

49. PHYSARUM GALBEUM Wing.

1890. Physarum galbeum Wing., Ell., N. A. F., 2491 (no description). 1892. Physarum petersii Berk. & C., Mass., Mon., p. 296, in part. 1894. 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 Philadelphia. The walls of the sporangia when fully matured generally break into several petal-like segments which finally become reflexed. The description given by Berkeley is entirely insufficient.

In an earlier edition this species was entered as P. obrusseum following the Polish text. Miss Lister who has the type of Didymium obrusseum at hand considers it as representing a phase of Physarum polycephalum Schw. D. tenerrimum Berk. & Curt. is judged the same. P. tenerum Rex is, in any event, certain, and the combination is adopted.

Rare:—Pennsylvania, Ohio, Louisiana, Texas, Iowa, Portugal, Japan.

51. PHYSARUM FLAVICOMUM Berk.

PLATE XV., Figs. 3, 3 a.

1845. Physarum flavicomum Berk., Hook. Jour. Bot., IV., p. 66. 1873. Physarum cupripes, Berk. & Rav., Grev., II., p. 65. 1875. Physarum berkeleyi Rost., Mon., p. 105. 1894. Physarum berkeleyi Rost., List., Mycetozoa, p. 57. 1899. Physarum flavicomum Berk., Macbr., N. A. S., p. 53. 1911. Physarum flavicomum Berk., List., Mycetozoa, 2nd ed., p. 58.

Sporangia gregarious, small, spherical, at first fuliginous throughout, stipitate; the peridium thin, destitute of lime, iridescent, breaking up and deciduous in patches, except at the base; stipe twice the diameter of the peridium, brown, fluted, not hollow, tapering upward from a small but distinct, radiant hypothallus; columella none; capillitium dense, persistent, the nodes frequently calcareous, elongate and vertical, especially below, yellow; spore-mass brown; spores by transmitted light, bright violaceous-brown, slightly papillose, 9-10 mu.

This species is instantly distinguishable from all cognate forms by its peculiar sooty color. Not less is the species structurally marked by its capillitium. The latter below is exactly as in the species of Tilmadoche. Indeed, the present species unites characters supposed to distinguish Physarum from Tilmadoche, and would so far justify those authors who bring all the species of both genera together under one generic name. In any case the species is by its capillitium entirely distinct from P. galbeum, as well as by the structure of the stipe and the peridial surface. The plasmodium, at first watery, emerges from decayed elm logs and soon takes on a peculiar greenish tint preserved somewhat in the mature fruit.

Rostafinski, Monograph, pp. 105, 106, rejects Berkeley's specific name, flavicomum, because it refers to the somewhat indefinite, characteristic color. As this is no valid reason for change, we have restored Berkeley's specific name, which by general consent has priority. N. A. F., 3299.

Not common. New Jersey, Ohio, South Carolina, Iowa.

52. PHYSARUM BETHELII (Macbr.) Lister.

1899. Tilmadoche bethelii, Macbr., Exempl. ad Herbaria. 1911. Physarum gyrosum Rost., List., Mycetozoa, 2nd ed., p. 75.

Sporangia scattered, globose, umbilicate below, .5-1 mm. in diameter, iridescent blue, or sometimes tinged by the presence of delicate pale yellow calcareous scales, stipitate; stipe rather short, black or dark brown, equal; capillitium dense, radiating from the black, slightly intrusive summit of the stipe, and from the base of the peridium ascending; the nodules not numerous, elongate, branching betimes, pale yellow; spores minutely roughened, 10-12 mu.

This beautiful delicately tinted little species is clearly tilmadochoid in the Friesian sense. The capillitium persists after the fall of the upper filmy peridium, adherent below to the persisting peridial base. Collected thus far twice only; by Professor Bethel and by Professor Sturgis, Colorado.

SECTION 2

Tilmadoche Fries

53. PHYSARUM GYROSUM (Rost.) Jahn.

1875. Physarum gyrosum Rost., Mon., p. 111. 1902. Physarum gyrosum Rost., Jahn, Ber. Deutsch. Bot. Ges., XX., p. 272, t. XIII. 1911. Physarum gyrosum Rost., List., Mycetozoa, 2nd ed., p. 75.

Sporangia gyrose, variable in form, or plasmodiocarpous and irregular, venulose, sessile upon a common, strongly developed hypothallus, sometimes isolated and irregularly globose, dehiscing irregularly or by longitudinal fissure, yellowish or greyish white; columella none; capillitium delicate, the nodules elongate, variable in size; spores pale violaceous, minutely spinulose, 7-10 mu.

This is a European species recently resuscitated by Dr. Jahn. It perhaps might more correctly be recorded as P. gyrosum Jahn, since Rostafinski certainly attempted in his description to cover two apparently distinct things. He seems to have had before him Fuligo muscorum Schw. and "P. gyrosum," but he thought them the same, and his description touches now one, now the other. Since F. muscorum Schw. has all along held its own and received due recognition, it is interesting to note the recovery of this gyrose form.

Judging by description and figures, it resembles a very large, sessile phase of P. polycephalum. See further under that species.

Europe, Japan, Eastern United States (?).

54. PHYSARUM POLYCEPHALUM Schw.

PLATE VIII., Figs. 2, 2 a, 2 b.

1822. Physarum polycephalum Schw., Syn. Fung. Car., No. 382. 1829. Didymium polycephalum (Schw.) Fries, Syst. Myc., III., p. 122. 1837. Didymium polymorphum Mont., Ann. Sci. Nat., Ser. 2, 8, p. 361. 1837. Didymium gyrocephalum Mont., op. cit., p. 362. 1875. Physarum polymorphum (Mont.) Rost., Mon., p. 107. 1875. Tilmadoche gyrocephala (Mont.) Rost., Mon., p. 131. 1899. Tilmadoche polycephala (Schw.) Macbr., N. A. S., p. 57. 1911. Physarum polycephalum Schw., List., Mycetozoa, 2nd ed., p. 58.

Sporangia spherical or irregular, impressed, gyrose-confluent, helvelloid, umbilicate below; peridium thin, ashy, covered with evanescent yellow squamules, fragile; stipe from an expanded membranaceous base, long-subulate, yellow; spores smooth, violet, 9-11 mu.

A most singular species and well defined is this, occurring in masses of decaying leaves or on rotten logs. The plasmodium at first colorless; as it emerges for fructification, white, then yellow, spreading far over all adjacent objects, not sparing the leaves and flowers of living plants; at evening slime, spreading, streaming, changing; by morning fruit, a thousand stalked sporangia with their strangely convoluted sculpture. The evening winds again bear off the sooty spores, and naught remains but twisted yellow stems crowned with a pencil of tufted silken hairs. August.

Although Rostafinski's description of this species is accurate and marks exactly a Tilmadoche and is very different from his description of Physarum polymorphum, nevertheless it is probable that both descriptions have reference to the same thing. All specimens on which both species were based were American; P. polymorphum, North American. But the only North American form to which reference can be made is that by Schweinitz called P. polycephalum and, fortunately, sufficiently described. Furthermore, Rostafinski, under T. gyrocephala, himself affirms the probable identity of Montagne's Didymium gyrocephalum with the Schweinitzian species, and uses Montagne's specific name provisionally. For these reasons it seems proper to write the species as above.

Widely distributed and common, from Maine and Canada to Nebraska, and Washington and south to Nicaragua.

This species is so common that its plasmodium and fructification may be easily observed. Professor Morton E. Peck, who has been for years a close observer of the vegetative phases of our Iowa species, says of P. polycephalum: "In one instance I observed a plasmodium for twelve successive days on the surface of a decaying stump. During this period it crept all around the stump and from top to bottom several times. At one time the color was bright yellow; at another, greenish yellow; and once, shortly before fruiting, it became clear bright green. A heavy rain fell upon the plasmodium but it appeared to sustain little injury and ultimately developed normal sporangia."

55. PHYSARUM NUTANS Pers.

1791. Sphaerocarpus albus Bull., Champ., p. 137, t. 407, III., and t. 470, I, A-L. 1791. Stemonitis alba (Bull.), Gmel., Syst. Nat., p. 1469 (?). 1795. Physarum nutans Pers., Ust. Ann. Bot., XV., p. 6. 1803. Trichia cernua Schum., Enum. Pl, Saell., II., p. 241. 1829. Physarum cernuum (Schum.) in part, Fr., Syst. Myc., III., pp. 130, 147. 1848. Tilmadoche cernua (Schum.) Fr., Summ. Veg. Sc., p. 454. 1873. Tilmadoche nutans (Pers.) Rost., Versuch, p. 10. 1899. Tilmadoche alba (Bull.) Macbr., N. A. S., p. 58. 1911. Physarum nutans Pers., List., Mycet., 2nd ed., p. 67, in part.

Sporangia gregarious, depressed-spherical, stipitate, umbilicate, gray or white, thin-walled, nodding; stipe long, tapering upward, brown or black below, ashen white above, lightly striate, graceful; capillitium abundant, threads delicate, intricately combined in loose persistent network with occasional minute, rounded, or elongate calcareous nodules; spores minutely roughened, globose, about 10 mu.

The nodding, lenticular, umbilicate sporangium, barely attached to the apiculate stipe, is sufficient to distinguish this elegant little species, recognized and quite aptly characterized by mycologists for more than one hundred years. As Sphaerocarpus albus Bulliard first prescribed the limits by which the species is at present bounded. The description by Fries (Syst. Myc.,, III., 128) is especially graphic; "Peridium very thin, in form quite constantly lenticular, umbilicate at base, at first smooth then uneven, generally laciniate-dehiscent, the segments persistent at least at base."

The stipe is usually white above, fuscous below, at the apex almost evanescent; hence the cernuous sporangia. The same character is less strikingly manifest in the species next following.

The plasmodium is bright yellow, sometimes greenish. Brought in from the field and maturing under a bell-jar, the color changes to a watery white just before the sporangia rise in fruit. P. album Fuckel, Rhen. Fl., No. 1469, 1865, is believed to be P. cinereum (Batsch) Pers.

Persoon changed Bulliard's specific name in this case to furnish one himself, more descriptive as he thought and distinctive. His success in this attempt must be esteemed but partial since all the related forms, immediately listed, nod as well. Bulliard's name as applied by Persoon is therefore to be preferred. But the transfer from Tilmadoche to Physarum loses for us one step in the ladder of priority. P. album (Bull.) may not enter here, since Fries has given us one species under that title. So Persoon comes next on the list, all the world now nodding approbation, let us hope!

Under the name Physarum gracilentum, Fries cites an extremely delicate form of this species. The sporangia are of the most minute, about .2-.3 mm. in diameter, globose, slightly umbilicate below, the stipe usually white at top, but sometimes black throughout. This graceful form occurs rarely in undisturbed woods.

Widely distributed in the eastern United States, apparently rare in the west. Reported from various parts of the world; Europe, Japan, Australia, etc.

56. PHYSARUM VIRIDE (Bull.) Pers.

PLATE VIII, Figs. 8, 8 a, 8 b.

1791. Sphaerocarpus viridis Bull., Champ., t. 407, Fig. I. 1791. Sphaerocarpus luteus Bull., Champ., t. 407, Fig. II. 1791. Sphaerocarpus aurantius Bull., Champ., t. 484, Fig. II. 1791. Stemonitis viridis (Bull.) Gmel., Sys. Nat., p. 1469. 1794. Physarum aureum Pers., Roemer, Neu. Mag. f. die Bot., I., p. 88. 1795. Physarum viride Pers., Usteri, Ann. Bot., XV., p. 6. 1801. Physarum aurantium Pers., Syn. Meth., p. 173. 1829. Physarum nutans var. Fries, Syst. Myc., III., pp. 128-129. 1875. Tilmadoche mutabilis Rost., Mon., p. 129. 1880. Tilmadoche viridis (Bull.) Sacc., Michelia, II., p. 263. 1894. Physarum viride Pers., List., Mycetozoa, p. 50. 1899. Tilmadoche viridis (Bull.) Sacc., Macbr., N. A. S., p. 59. 1911. Physarum viride Pers., List., Mycetozoa, 2nd ed.

Sporangia globose, flattened or lenticular, beneath plane or concave, variously colored, yellow, greenish yellow, rusty orange, stipitate, nodding; the peridium splitting irregularly or reticulately; stipe variable in length and color, through various shades of red and yellow, subulate; capillitium strongly developed, concolorous with sporangium, the tubes with colorless or yellow calcareous thickenings; spores smooth, fuscous or violet-black, 8 mu.

A very handsome and rather common little species; like the preceding, but generally greenish-yellow in color, and occasionally brilliantly orange without a suggestion of green. Indeed, the color is so variable that some authors have been disposed to discard the species entirely, inasmuch as the chief specific character is color. The plasmodium is pale yellow, in rotten logs, stumps, etc. In the paler yellow or greenish forms the stipe is more commonly black.

This is Physarum luteum (Bull.) Fries, and likewise also includes the three varieties, viride, aureum, coccineum, listed by the same author under P. nutans, while he at the same time remarks that they might with equal propriety be elsewhere referred. Rostafinski considers that all the colored forms agree in capillitium sufficiently to be associated under one name and are in the same way unlike T. nutans.[29] Rostafinski thinks to avoid confusion by suggesting a more fitting specific name, T. mutabilis, but there seems no good reason for not adopting the earliest identifiable specific appellation, which in this case appears to be viride. The yellow phase is common in Iowa, resembles in size, color, stipe, P. galbeum Wingate, but is instantly distinguishable by the capillitium. N. A. F., 1213.

Widely distributed specimens are before us;—from New England, New York, Pennsylvania, Maryland, Ohio, Nebraska, Iowa, California, Oregon, Canada, Nicaragua, Samoa, Alaska, India, etc.

EXTRA-LIMITAL[30]

PHYSARUM MUTABILE (Rost.) List.

1875. Crateriachea mutabilis Rost., Mon., p. 125. 1892. Crateriachea mutabilis Rost., Mass., Mon., p. 344. 1894. Physarum cinereum List., Mycetozoa, p. 55, in part. 1895. Physarum crateriachea List., Jour. Bot., XXXIII., p. 323. 1910. Physarum crateriachea List., Petch, Mycetozoa Ceylon, p. 336. 1911. Physarum mutabile List., Mycetozoa, 2nd ed., p. 53.

Sporangia cylindrical ovoid or sub-globose white, plasmodiocarpous, sessile or stipitate, stipes when present yellow, with or without lime, often connected by a hypothallus; peridium thin, squamulose; capillitium persistent, intricate, the nodules white, more or less confluent at the center to form a real or a pseudo-columella; spores brownish-purple, spinulose, 7-8 mu.

Reported from Europe, Africa, Ceylon.

PHYSARUM ROSEUM Berk. & Br.

1873. Physarum roseum Berk. & Br., Jour. Linn. Soc., XIV., p. 84.

Plasmodium rose-red; sporangia gregarious, stipitate, globose, rose-red; the stipe erect, brown, rugulose, translucent; capillitium lax, delicate, lilac, the nodules few, large, purple-red, branching; spores reddish-lilac or brown, minutely spinulose, 7-10 mu.

Reported from Ceylon, Java, Borneo, Japan.

PHYSARUM DICTYOSPERMUM List.

1905. Physarum dictyospermum List., Jour. Bot., Vol. XLIII., p. 112.

"It is distinguished from the other known species of Physarum by the strongly reticulated spores. Its nearest ally is perhaps P. psittacinum which it resembles in having orange-red lime-knots and in the sporangium-wall being studded with orange crystalline disks." Lister.

Reported collected once only; New Zealand.

PHYSARUM STRAMINIPES List.

1898. Physarum straminipes List., Jour. Bot., Vol. XXXVI., p. 163.

Plasmodium white; sporangia greyish-white, obovoid or wedge-shaped, .7 mm. in diameter, clustered or scattered, stipitate or sessile, when stipitate stalks long, weak; peridium membranous, pale purple; capillitium a persistent rigid net, the nodules white, rounded, sometimes aggregate as a pseudo-columella; spores purple-brown, 10-11 mu, warted, the papillae in definite patches.

Related to P. compressum.

Reported from England; Germany.

PHYSARUM CRATERIFORME Petch.

Physarum crateriforme Petch, Ann. Perad., IV., p. 304. Physarum crateriforme Petch, List., Mycetozoa, 2nd ed., p. 69, Pl. 76.

Sporangia gregarious, globose, clavate or crateriform, sessile or stipitate, white; stalk when present opaque conical, black below, white above, in crateriform sporangia entering and developed as a columella; capillitium various, strongly calcareous, the nodules either grouped in a pseudo-columella, or in globose sporangia, rod-like, ascending; spores closely spinulose, 11-15 mu.

Reported from Ceylon, Japan, West Indies; Lisbon.

PHYSARUM GULIELMAE Penzig.

1898. Physarum gulielmae Penzig., Myx. Beut., p. 34. 1909. Physarum gulielmae Penzig., Torrend, Fl. des Myx., p. 208. 1911. Physarum gulielmae Penzig., List., Mycetozoa, 2nd ed., p. 76.

Plasmodium yellow; sporangia sub-globose, sessile, brownish-orange or chestnut brown, rugulose, clustered or heaped, often with a yellow membranous hypothallus; peridium membranous with clustered deposits of yellowish-brown lime granules; capillitium abundant, the nodes angular, branching, white; spores purplish brown, spinulose, 10-12 mu.

Reported from Java, Sweden, Switzerland.

PHYSARUM ECHINOSPORUM List.

1899. Physarum echinosporum List., Jour. Bot., XXXVII., p. 147.

This species is distinguished from the preceding chiefly in episporic characters. "Spores purple, 8 mu, marked by strong ridges and spines," 8 mu.

Reported from Antigua.

PHYSARUM AENEUM (List.) R. E. Fries.

1898. Physarum murinum var. aeneum Lister, Jour. Bot., XXXVI., p. 117. 1903. Physarum aeneum Lister, R. E. Fries, Arkiv. Bot., I., p. 62.

Sporangia sessile, sub-globose or plasmodiocarpous, pinkish-brown or bronze, glossy; peridium double, the outer somewhat cartilaginous, brittle, falling back from the shining, membranous inner wall; capillitium dense, the nodules not large, brown, sometimes aggregated to form a pseudo-columella; spores pale brownish-violet, nearly smooth, 6-8 mu.

Reported from West Indies, Bolivia.

Related Genus

TRICHAMPHORA Junghuhn, p. 12.

1838. Trichamphora, Junghuhn, Fl. Crypt. Javanica.

Sporangia discoidal, above concave, saucer-shaped, stipitate; the capillitium variable, anon physaroid, badhamioid, or even as in Didymium.

This genus is set up for the accommodation thus far of the single species following. It differs from Physarella in the apparently constant discoidal shape, absence of trabecules, etc.

TRICHAMPHORA PEZIZOIDEA Jungh., op. cit.

1838. Trichamphora pezizoidea Jungh., op. cit. 1854. Didymium zeylanicum Berk. & Br., Hook. Jour. Bot., VI., p. 230. 1869. Physarum macrocarpum Fuckel, Symb. Myc., p. 343. 1875. Chondrioderma pezizoidea Rost., Mon., p. 424, tab. VIII., Fig. 122. 1876. Badhamia fuckeliana Rost., Mon., App., p. 2. 1894. Trichamphora pezizoidea Jungh., List., Mycetozoa, p. 89. 1911. Trichamphora pezizoidea Jungh., List., Mycetozoa, 2nd ed., p. 90.

Sporangia discoidal or saucer-shaped, gregarious, stipitate, erect or nodding, grayish-white, the peridium thin, breaking irregularly and persistent; stipe subulate, striate, reddish brown, transparent; capillitium variable as above stated; spores pale violet-brown, spinulose or nearly smooth, about 9 mu.

In Mycetozoa, 2nd ed., the spores are described as "dark or pale purplish brown, spinose, spinulose or nearly smooth, 9-17 mu in diameter." This would seem too great a variation even in this protean species. The only specimens in our herbarium are from the Congo valley. The spores are pale and nearly smooth, as in Tilmadoche alba, and 9 mu. Spores 17 mu suggest immaturity; penultimate cell-division.

The synonymy above cited shows how this species has impressed careful students. Doubtless in every case the reference is correct, judging from the specimen each author had before him, although it is hard to see how Chondrioderma might have been suggested.

The species is evidently tropical, though reported from Europe.

4. Craterium Trentepohl

1797. Craterium Trentepohl, Roth, Catal., I., p. 224.

Sporangia more or less distinctly cyathiform, stipitate, the peridium generally plainly of two layers or even of three, opening at the top by circumscission more or less definite, or by a distinct lid, the upper part calcareous often to a marked degree, the lower, cartilaginous, long persistent as a vasiform cup containing the capillitium and spores, the calcareous nodes aggregating more or less to form a pseudo-columella.

This genus is distinguished from Physarum and Badhamia chiefly by the form of the sporangia and the method of dehiscence. The capillitium is in some specimens particularly, of the Physarum type; in others, like that of Badhamia. There are accordingly species that receive at the hands of different authors diverse generic reference as one feature or another in the structure is emphasized in the different cases. It is granted that it is hard to draw the line sometimes between forms in which the dehiscence is irregularly circumscissile and those in which the wall breaks without any regularity whatever, since, in all, the breaking up of the peridium usually begins at the top. Species here included will, however, offer little ambiguity.

Key to the Species of Craterium

A. Dehiscence circumscissile or by the breaking up of the upper wall of the sporangium.

a. Sporangia violet or purple 1. C. paraguayense

b. Sporangia yellow 2. C. aureum

c. Sporangia white-capped.

1. Sporangia obovoid or globoid 3. C. leucocephalum

2. Sporangia cylindric, elongate 4. C. cylindricum

B. Dehiscence by a distinct lid.

a. Capillitium pale brown 5. C. concinnum

b. Capillitium white 6. C. minutum

1. CRATERIUM PARAGUAYENSE (Speg.) List.

1883. Didymium paraguayense Speg., Fung. Guar. Pug., 1, p. 141. 1893. Craterium rubescens Rex, Proc. Philad. Acad. Nat. Sci., p. 370. 1894. Craterium rubescens Rex, List., Mycetozoa, p. 71. 1899. Craterium rubescens Rex, Macbr., N. A. S., p. 75. 1904. Iocraterium paraguayense (Speg.) Jahn, Hedwigia, XLII., p. 302. 1911. Craterium paraguayense List., Mycetozoa, 2nd ed., p. 95.

Sporangia gregarious, cylindrical or elongate cyathiform, stipitate, dark violet-red, the apex slightly roughened by pale calcareous granules, the peridium longitudinally wrinkled below; dehiscence, irregularly circumscissile; stipe darker, one-half the height of the sporangium, longitudinally wrinkled; capillitium dense, abundantly calcareous; spores violet-brown, minutely roughened, 7-8 mu.

In form resembling the following species, but instantly distinguished by the color, which is red throughout, tinged with purple or violet. The capillitium is badhamioid, as noted by Dr. Rex. Very distinct from P. newtoni in color, form, habit, epispore, etc.

2. CRATERIUM AUREUM (Schum.) Rost.

1803. Trichia aurea Schum., Enum. Pl. Saell., II., p. 207. 1829. Craterium mutabile Fries, Syst. Myc., III., p. 154. 1875. Craterium aureum (Schum.) Rost., Mon., p. 125.

Sporangia gregarious, globose or obovoid, stipitate, yellow, erect, the peridial wall thin, especially at the summit, where at maturity it breaks up somewhat reticulately, leaving the persistent lower portion with an uneven margin above which projects the pale yellow capillitium; stipe short, orange, or brownish-red, arising from a small hypothallus; capillitium dense, yellow, the nodules not large, irregular, tending to form a pseudo-columella in the centre of the cup; spores minutely warted, violaceous-brown, 8-10 mu.

Fries regards this, which he names C. mutabile, the most distinctly marked species of the genus; chiefly, as it appears, on account of the bright yellow color. This, however, varies. Some specimens before us are gray, showing only a trace of yellow below. In some European specimens a reddish tinge prevails. The form of the sporangium also varies. In typical specimens, unopened, the shape is almost pyriform; opened, we have a cylindric, oftenest lemon-yellow vase, mounted on a short striate stalk. But again, from the same plasmodium, we may have globose sporangia, opening so as to leave only a shallow, salver-shaped base. In this case the stipe is also longer. The plasmodium is said to be "clear lemon yellow."—Massee.

There seems little doubt that Schumacher had in mind the present species in his Trichia aurea. Rostafinski shows that Fries's synonym, C. mutabile, is founded on a mistake. The earlier specific name is therefore on Rostafinski's authority adopted.

Not common. Pennsylvania, New Jersey, North Carolina, Ohio, Iowa.

3. CRATERIUM LEUCOCEPHALUM (Pers.) Ditmar.

PLATE VIII., Fig. 5.

1791. Stemonitis leucocephala Gmelin, Syst. Nat., II., p. 1467. 1801. Arcyria (?) leucocephala Persoon, Syn. Fung., p. 183. 1801. Craterium (?) leucocephalum, Persoon, Syn. Fung., p. 184. 1813. Craterium leucocephalum (Pers.) Ditmar, Sturm, Deutsch. Flora, Pilze, p. 21, Pl. 11. 1889. Physarum scyphoides Cke. & Balf., Jour. Myc., V., p. 186. 1896. Craterium convivale (Batsch) Morg., Jour. Cin. Soc., p. 86.

Sporangia gregarious, short-cylindric or ovate, pure white above, brown or reddish-brown below, stipitate, dehiscence irregularly circumscissile, the persistent portion of the peridium beaker-shaped; stipe short, stout, expanded above into the base of the peridium with which it is concolorous; hypothallus scant; capillitium white or sometimes, toward the centre, brownish, the calcareous nodules large, conspicuous, and persistent; spore-mass black, spores violaceous-brown, minutely spinulose, 8-9 mu.

Distinguished by its white cap from all except the next, from which the markedly different form serves as the diagnostic feature. In some gatherings, curious patches of yellow mark the otherwise snow white cap and sides; these are mere stains, or sometimes definite, crystalline, flake-like bodies, standing out in plain relief on the sporangial wall, or lurking in the larger nodules which are massed along the axis of the cup to form the pseudo-columella here strongly developed. Mr. Lister calls attention to these yellow flakes, and regards them as diagnostic. European specimens show the capillitium yellow, sometimes throughout!

The nomenclature question is here somewhat difficult. Fries heads his list of synonyms with Peziza convivalis Batsch. Batsch simply described Micheli's figure! Now there is nothing in Micheli's figure (Pl. 86, Fig. 14) to enable one to say with certainty which craterium Micheli had in mind, if craterium at all. Nor does Batsch help the matter when he offers the description following: "Stipitata; acute conica, patens; stipite subdistincto, lineari, brevi, valido. Albicans. In foliis hederae putridis." (Elenchus Fungorum, Batsch, 1783, p. 121.) There is nothing definitive here but the one word "albicans" quoted from Micheli. But this term is applicable the rather to C. minutum, the cups of which whiten with weathering. It may be, as insisted by Fries (Syst. Myc., III., p. 149), that Micheli drew crateriums; but if so, we cannot determine which species.

The specific name here adopted was applied by Persoon probably to this form; but Persoon likewise failed to distinguish the present species from C. minutum (see Syn. Fung., pp. 183, 184), and Fries, op. cit., p. 153. Ditmar, l. c., leaves no doubt as to what he figures and describes, and accordingly the name he first correctly uses is here adopted.

Not common. New England, Pennsylvania, Ohio, North Carolina, Iowa, Colorado, Washington, California; reported from Europe.

4. CRATERIUM CYLINDRICUM Massee.

PLATE XVI., Fig. 2.

1873. Craterium minimum Berk. & C., Grev., II., p. 67. 1892. Craterium cylindricum Massee, Mon., p. 268. 1894. Craterium leucocephalum Ditm., List., Myc., p. 72, in part. 1899. Craterium minimum Berk. & C., Macbr., N. A. S., p. 77. 1911. Craterium leucocephalum var. cylindricum List., Mycetozoa, 2nd ed., p. 97.

Sporangia closely gregarious, very small, .5 mu or less, slender, cylindric, almost entirely white, stipitate, the peridium delicate, transparent although calcareous nearly to the base, opening by a dehiscence regularly circumscissile; stipe short, about one-third the total height, clear orange-brown, somewhat furrowed, rising from an indistinct hypothallus; capillitium very lax, physaroid, the calcareous nodules large, rounded, pure white, aggregated at the centre of the cup; spore-mass black, spores minutely roughened, violaceous-brown, 8-9 mu.

This is the common form in the United States. Massee describes it as C. cylindricum Mass., and it seems not to occur in Europe. Lister has put it in with C. leucocephalum, from which its more delicate structure and elegant cylindrical shape certainly distinguish it. The dehiscence is even more regular than in the preceding species and approaches that of C. minutum Leers., with bleached forms of which it must not be confused. N. A. F., 1400.

C. minimum Berk. & C. has here priority. Massee regards this name as indicating a distinct species. We have been unable to determine what the authors really had before them, and adopt accordingly the first available combination.

New England to Iowa and south; reported also from the orient.

5. CRATERIUM CONCINNUM Rex.

1893. Craterium concinnum Rex, Proc. Phila. Acad., p. 370.

Sporangia scattered, usually minute, broadly funnel-shaped, stipitate. The peridium simple, variously colored by innate lime granules, opening by a regular cap or operculum, brownish white, darkest in the centre, always more or less convex; stipe equalling the cup in height, dark brown, longitudinally ridged; the capillitium a close-meshed network, with small rounded or slightly angular masses of ochre-brown lime-granules, larger toward the centre; spores pale brown, minutely warted, 9-10 mu.

This species differs from the following, to which it seems most nearly allied, in form, color, as in the capillitium, and color of the spores. In habitat, however, it seems no less distinct, being found always (?) on the spines of decaying chestnut-burs lying on the ground, and in company with that other peculiar species Lachnobolus globosus.

The range is probably that of the chestnut, Castanea dentata Borkhausen, east of the Mississippi River.

6. CRATERIUM MINUTUM (Leers) Fr.

PLATE XV., Fig. 5.

1775. Peziza minuta Leers, Fl. Herborn, p. 277. 1797. Craterium pedunculatum Trent., Roth., Catal. Bot., I., p. 224. 1813. Craterium vulgare Ditmar, Sturm, Deutsch. Fl. Pilze, p. 17. 1829. Craterium pedunculatum Trent., Fr., Syst. Myc., III., p. 150. 1829. Craterium minutum Leers, Fr., Syst. Myc., III., p. 151. 1893. Craterium pedunculatum Trent., Macbr., Bull. Lab. Nat. Hist. Iowa, II, p. 385. 1894. Craterium pedunculatum Trent., Lister, Mycetozoa, p. 70. 1899. Craterium minutum (Leers) Fr., Macbr., N. A. S., p. 78. 1911. Craterium minutum Fr., List., Mycetozoa, 2nd ed., p. 94.

Sporangia scattered, gregarious, cyathiform or turbinate, grayish brown, stipitate, the peridial wall rather thick, double, opening by a distinct lid which lies usually below the slightly thickened and everted margin of the cup; stipe paler, translucent, about equalling in height the peridial cup, longitudinally wrinkled, with hypothallus scant or none; capillitium physaroid, the calcareous nodules large, white, and generally aggregated at the centre of the cup; spore-mass black, spores by transmitted light violaceous, minutely warted, 8-10 mu.

This is the most highly differentiated of the whole series. The cup is shapely and well defined, while the lid is not only distinct, but is a thin, delicate membrane of slightly different structure when compared with the peridial wall. It is in all the specimens before us much depressed below the mouth of the sporangium, and the whole structure in our specimens corresponds with Fries' description of C. pedunculatum Trent., while specimens received from Europe correspond to Fries' account of C. minutum Leers. Nevertheless we are assured that the two forms are in Europe developed from the same plasmodium, and therefore adopt the earlier specific name as above. N. A. F., 2500. This is probably Fungoides convivalis of Batsch and Micheli.

In this species yellow sporangia are sometimes seen. Miss Currie reports from Toronto such variation and in Europe the case seems not unusual.

In fact, there is a yellow tinge about the sporangia of every species listed here, except the first. With the same exception, the plasmodium in every case is yellow.

Common throughout the eastern United States, west to Iowa, Colorado, and south to Louisiana; cosmopolitan.

5. Physarella Peck.

1882. Physarella Peck, Bull. Torr. Bot. Club, IX., p. 61.

Sporangium pervious to the base, the interior walls forming a persistent spurious columella; capillitium composed of filaments with here and there minute knot-like thickenings, straight tubes containing lime-granules extending from the exterior to the interior walls of the sporangium, persistently attached to the former.[31]

Such is Dr. Peck's original description of this most peculiar genus. The form of the sporangium in the only species is very variable, but in typical cases is vasiform, the peridial wall at the apex introverted. The capillitium is like that of Tilmadoche, except for the presence of the "straight tubes" emphasized in the original description. These are very remarkable and at once diagnostic. They take origin in the sporangial wall and pass across to the "columella"; but at the dehiscence of the sporangium, in typical cases, they remain attached at the points of origin, projecting as stout spine-like processes.

PHYSARELLA OBLONGA (Berk. & C.) Morg.

PLATE VIII., Figs. 4, 4 a, 4 b, 4 c; PLATE XVI., Figs. 1, 1 a, 1 b, and 6.

1873. Trichamphora oblonga Berk. & C., Grev., II., p. 66. 1876. Tilmadoche oblonga (Berk. & C.) Rost., Mon. App., p. 13. 1876. Tilmadoche hians Rost., Mon. App., p 14. 1882. Physarella mirabilis Peck, Bull. Torr. Bot. Club, IX., p. 61. 1893. Physarella oblonga (Berk. & C.) Morg., Jour. Cin. Soc., p. 79. 1894. Physarella mirabilis Peck, List., Mycet., p. 68. 1899. Physarella oblonga (Berk. & C.) Morg., Macbr., N. A. S., p. 71. 1911. Physarella oblonga Morg., List., Mycet., 2nd ed., p. 91.

Sporangia scattered or gregarious, typically cup-shaped or sub-infundibuliform, stipitate, erect or cernuous, but varying through low salver-shaped cups, to irregular applanate and sessile masses, the peridium thin but firm, tawny, roughened by numerous yellowish calcareous scales, at length ruptured above and often reflexed in the form of petal-like segments from which project upwards the spiniform trabecules of the capillitium; stipe when present long, terete, red, arising from a scant hypothallus and extended within the sporangium to meet the tubular "columella"; capillitium of delicate violaceous threads seldom branched or united, radiating from the columella with few calcareous nodular expansions, but supported by stout yellow calcareous trabecules, running parallel to the capillitial threads, long adherent to the sporangial wall; spores smooth, globose violet-brown, 7-8 mu.

Not uncommon in wet places. New York, Ohio, Iowa, South Dakota, Louisiana, Nicaragua; reported also from Ceylon, Java, etc.

Not the least remarkable feature of this remarkable species is the variation in the form of the fruit or sporangia. We have specimens from Louisiana (Rev. Langlois) which show no trace of columella, the whole structure involute and plicate, short stipitate, recalling the extremest complexity of such a species as P. polycephalum. Vid. Pl. XVI., Fig. 6. Moreover, in these specimens the calcareous deposits are white and not yellow, giving the entire fructification a grayish aspect. Yet there is no doubt we have here simply an exaggerated abnormality of the species; the spores are identical in size, color, and surface. Plasmodium bright yellow. Dr. Peck gave to his forms the name Physarella mirabilis; but specimens sent by Michener of Pennsylvania, and by Berkeley and Curtis described as Trichamphora oblonga (Grev., II., p. 66), are the same thing. N. A. F., 1212.

Physarella lusitanica Torrend is a globose form depressed above or betimes discoidal, occurring on Eucalyptus trees in Portugal. P. oblonga is so variable in form that it sometimes suggests a different genus. Forms of it have been mistaken for Fuligo gyrosa R., etc. Professor Torrend would include here Physarum javanicum (Rac.), i. e. Tilmadoche javanica as Raciborski saw it! We may not too often reflect that genera are purely artificial things set up for our convenience; but surely Physarella as a natural genus is distinct enough to all.

6. Cienkowskia Rost.

1873. Cienkowskia Rost., Versuch, p. 9.

Fructification plasmodiocarpous, irregularly dehiscent, the wall a thin cartilaginous membrane destitute of lime, except the capillitial attachments within; capillitium scanty but rigid, and characterized everywhere by peculiar hook-like branchlets, free and sharp-pointed, the spores as in Physarum, etc.

The genus contains, so far, but a single species:—

CIENKOWSKIA RETICULATA (Alb. & Schw.) Rost.

PLATE XIV., Figs. 2, 2 a, 2 b.

1805. Physarum reticulatum Alb. & Schw., Cons. Fung., p. 90. 1829. Diderma reticulatum Fr., Syst. Myc., III., p. 112. 1873. Cienkowskia reticulata (Alb. & Schw.) Rost., Versuch, p. 9.

Plasmodiocarp an elongated, irregularly limited, close-meshed net, closely applied to the substratum, the wall thin, transversely rugulose, and roughened, dull orange-yellow, splashed here and there with scarlet, anon entirely red, within marked by transverse calcareous ridges, supporting in part the calcareous system of the capillitium; capillitium of delicate, rigid, reticulating yellow tubules or threads with numerous free, uncinate or sickle-shaped branchlets, and large, irregular, calcareous plates, more or less transverse to the axis of the sporangium, attached to the peridial walls, as if to form septa, ordinary calcareous nodules few; spore-mass jet-black, spores, by transmitted light, violaceous, minutely roughened, 9-10 mu.

A very rare species, as it appears, easily recognized by the Coddington even, much more by the microscopic characters quoted; probably often overlooked by the collector, as to the naked eye it presents the appearance of some imperfectly developed, dried-up plasmodium. Very unlike Physarum serpula Morgan, not infrequently offered by collectors as Cienkowskia. It is Diderma reticulatum of Fries, who, strangely enough, thought it might be a plasmodial phase of Diderma (i. e. Leocarpus) fragile (Syst. Myc., III., p. 102).

Eastern United States, Europe, Java, Ceylon, California. See under L. fragilis, next following.

7. Leocarpus (Link) Rost.

1809. Leocarpus Link, Diss., I., p. 25.

Sporangia sessile, or short stipitate; peridial wall double, the outer thick, destitute of lime, polished, shining within and without, the inner very delicate, enclosing the capillitium and spores; capillitium of two, more or less, distinct systems, the one a delicate network of hyaline, limeless threads, the other calcareous throughout, or nearly so, the meshes large and the threads or tubules broad; columella none, although a pseudo-columella may sometimes be detected.

This genus was by Link established on characters purely external. Rostafinski supplemented Link's definition by calling attention to the peculiar character of the capillitium and to microscopic characters in general. The outer peridium is thick and strong, unlike the ordinary structure in Physarum. Some physarums, however, have a very similar outer wall; P. brunneolum, for instance; compare the peridium of P. citrinellum. In dehiscence and structure there is also some resemblance to some species of Diderma, and by Persoon and Fries the common species was so referred, but the capillitium is again definitive.

A critical study of all these things really begins with Rostafinski's microscope. Under his definition of the present genus P. squamulosum Wingate and P. albescens Ell. might well be entered here. Such course at present would but increase confusion, and until by future research the ontogeny of all these, and so their relationship, shall be more exactly known, the genus may be left with its historic species,—montotypic.

LEOCARPUS FRAGILIS (Dickson) Rost.

PLATE VIII., Figs. 3, 3 a, 3 b.

1785. Lycoperdon fragile Dickson, Fasc. Pl. Crypt. Brit., I., p. 25. 1795. Diderma vernicosum Persoon, Ust. Ann. Bot., XV., p. 34. 1809. Leocarpus vernicosum Link, Diss., I., p. 25. 1875. Leocarpus fragilis (Dicks.) Rost., Mon., p. 132.

Sporangia gregarious or clustered, sessile or stipitate, obovoid, rusty or spadiceous-yellow, shining; peridium opening at maturity in somewhat stellate fashion; stipe filiform, white or yellow, weak and short; spores dull black, spinulose, 12-14 mu.

A common species, distributed through all the world, Iowa to Tasmania. Recognizable at sight by the form and color of the sporangia. In shape and posture these resemble the eggs of certain insects, and, occurring upon dead leaves, generally where these have drifted against a rotten log, they might perchance be mistaken for such structures. With no other slime-moulds are they likely to be confused. The outer peridium opens irregularly, or more rarely stellately. At centre of the capillitium is a calcareous core. The plasmodium is yellowish white, spread in rich and beautiful reticulations. N. A. F., 1123.

A plasmodiform gathering of this species which will be mistaken for an entirely different thing, is yellow, sessile, and has adherent spores; looks like a badhamia, but is after all a leocarpus and probably belongs here. The spores are irregularly clustered and the badhamioid section of the capillitium seems now dominant.

California.

B. DIDYMIACEAE

Key to the Genera of the Didymiaceae

1. Fructification aethalioid 1. Mucilago

2. Fructification plasmodiocarpous, or forming more often distinct sporangia.

a. Calcareous deposits crystalline, stellate 2. Didymium

b. Calcareous deposits amorphous, peridium double 3. Diderma

c. Calcareous deposits in form of scattered scales 4. Lepidoderma

d. Peridium double, the outer gelatinous 5. Colloderma

1. Mucilago (Mich.) Adans.

1729. Mucilago Micheli, Nov. Pl. Gen., in part. 1763. Mucilago (Mich.) Adanson, Fam. des Pl., II., p. 7. 1791. Spumaria Pers. in Gmelin, Syst. Nat., II., p. 1466.

Fructification aethalioid, consisting generally of large cushion-shaped masses covered without by a white foam-like crust; within, composed of numerous tubular sporangia, developed from a common hypothallus, irregularly branched, contorted and more or less confluent; the peridial wall thin, delicate, frosted with stellate lime-crystals, which mark in section the boundaries of the several sporangia; capillitium of delicate threads, generally only slightly branched, terminating in the sporangial wall, marked with occasional swellings or thickenings.

By the descriptions offered by most authors, and especially by Rostafinski's figures (Mon., Pl. ix.), a pronounced columella is called for in the structure of Spumaria. The individual sporangia rise from a common hypothallus, and occasionally portions of this run up and give to a sporangium the appearance of being stipitate. Sometimes also this upper extension of the hypothalline protoplasm passes beyond or behind the base of the sporangium or between two or more, and is more or less embraced by these in their confluent flexures. This, it seems, suggested Rostafinski's elaborate diagram, Fig. 158; at least, none other form of columella is shown by American materials at hand.

1. MUCILAGO SPONGIOSA (Leyss.) Morgan.

PLATE VII, Figs. 6, 6 a, 6 b.

1783. Mucor spongiosus Leysser, Fl. Hal., p. 305. 1791. Reticularia alba Bull., C. Fl. France, p. 92. 1791. Spumaria mucilago Pers., Gmel., Syst. Nat., II., 1466. 1805. Spumaria alba (Bull.) DC., Fl. Fr., II., p. 261. 1897. Mucilago spongiosa (Leyss.) Morg., Bot. Gaz., XXIV., p. 56.

Aethalium white or cream-colored, of variable size and shape, half-an-inch to three inches in length and half as thick, the component sporangia resting upon a common hypothallus and protected by a more or less deciduous calcareous porous cortex; peridial walls thin, and where exposed iridescent, generally whitened by a thin coating of lime crystals; capillitium scanty, of simple, mostly dark-colored, slightly anastomosing threads; columella indefinite or none; hypothallus white, spongy; spore-mass black, spores violaceous, exceedingly rough, large, 12-15 mu.

Very common in all the eastern United States and the Mississippi valley, south to Texas. The plasmodium is dull white, of the consistence of cream, and is often met with in quantity on beds of decaying leaves in the woods. In fruiting the plasmodium ascends preferably living stems of small bushes, herbaceous plants, or grasses, and forms the aethalium around the stem some distance above the ground. The cortex varies in amount, is also deciduous, so that weathered or imperfectly developed forms probably represent the var. S. cornuta Schum.

Two varieties of this species are recognized; the one from Bolivia, var. dictyospora described by Mr. R. E. Fries (Arkiv. for Botanik Bd. 1, p. 66) differs from the type chiefly in its finer capillitial threads its darker spores with longer spines and fine reticulate sculpture; the other from Colorado, var. solida described by Professor Sturgis differs, as the name implies, principally in its greater compactness and slightly smaller calcareous crystals; a desert phase.

2. Didymium (Schrad.) Fr.

1797. Didymium Schrad., Nov. Gen. Plant., p. 20, in part. 1829. Didymium (Schrad.) Fr., Syst. Myc., III., p. 113. 1875. Didymium (Schrad.) DeBy., Rost., Versuch, p. 13.

Sporangia distinct, stipitate, sessile or even plasmodiocarpous, never aethalioid; the peridium thin, irregular in dehiscence, covered with a more or less dense coating of calcareous crystals; columella more frequently present; capillitium of delicate threads, simple or sparingly branched, extending from the columella to the peridial wall.

The genus Didymium, as set up by Schrader l. c., included a number of species now assigned to Diderma, Lepidoderma or Lamproderma. Fries set out the didermas; DeBary and Rostafinski completed the revision by setting out the remaining alien forms.

The genus is among Myxomycetes instantly recognized by the peculiar form of its calcareous deposits, stellate crystals coating, or merely frosting, usually distinct sporangia.