Key to the Species of Didymium

1. Lime-crystals merely whitening the peridial wall.

A. Fructification plasmodiocarpous.

a. White.

O Capillitium with adherent vesicles 1. D. complanatum

OO Capillitium simple 2. D. anellus

OOO Capillitium much combined; spores 10-13 mu 3. D. wilczekii

OOOO Capillitium crystal-bearing 18a. D. anomalum

b. Yellow or tawny 4. D. fulvum

B. Fructification normally of distinct sporangia.

a. Sporangia sessile or nearly so; outer calcareous wall conspicuously developed 5. D. crustaceum

b. Sporangia plainly stipitate.

i. Peridium much depressed; umbilicate below.

O Stipe white 6. D. squamulosum

OO Stipe black.

+ Larger, about 7.5-1 mm. 7. D. melanospermum

+ Small, about .5 mm. 8. D. minus

+ Sporangia discoid 9. D. clavus

ii. Peridium small, globose.

O Stipe dark brown or black; columella dark, obsolete or none. 10. D. nigripes

OO Stipe generally paler, of various tints of brown, orange, etc.

+ Columella pale or white, nearly smooth 11. D. xanthopus

+ Columella, yellow, discoid, rough 12. D. eximium

iii. Peridium turbinate, columella hemispheric 13. D. trochus

iv. Peridium annulate 14. D. annulatum

2. Calcareous crystals forming a distinct crust.

A. Fructification wholly plasmodiocarpous 15. D. dubium

B. Sporangia ill-defined, sessile, plasmodiocarpous.

a. Spores generally nearly smooth 16. D. difforme

b. Spores very rough, obscurely banded 17. D. quitense

EXTRA-LIMITAL

a. Sporangia discoid, spores reticulate 18. D. intermedium

b. Stipe, columella, peridium, orange-brown 19. D. leoninum

1. DIDYMIUM COMPLANATUM (Batsch) Rost.

PLATE XVI., Fig. 8.

1786. Lycoperdon complanatum Batsch, Elench. Fung., I., p. 251. 1829. Didymium serpula Fr., Syst. Myc., III., p. 126, Rost., App., p. 21. 1875. Didymium complanatum (Batsch), Rost., Mon., p. 151. 1899. Didymium complanatum (Batsch) R., Macbr., N. A. S., p. 85. 1911. Didymium complanatum Rost., List., Mycetozoa, 2nd ed., p. 127.

Fructification plasmodiocarpous, creeping, flattened, vein-like, annulate or reticulate, the dark-colored peridium covered with white, but not numerous crystals; hypothallus none; columella none; capillitium much branched, violaceous threads combined to form a rather dense net which bears numerous, peculiar, rounded vesicles, yellowish in color, 30-50 mu in diameter; spores minutely warted, 7-9 mu, violaceous-brown.

The defining characteristics here are the curious supplementary vesicles. These are evidently plasmodic, embraced, shot-through, by all the neighboring capillitial threads, withal warted like a spore. They remind of the curious, belated, spore-like but giant cells found in stipes, as in arcyriaceous forms. With all the wealth of his prolix, poetic, metaphoric tongue, the Polish author gives them abundant consideration. In the Mon., Tab. IX., Figs. 166 and 180, he clearly shows the structure, although in the explanation of the plate he has strangely mixed this species with D. crustaceum Fr. Under D. serpula Fries may refer to the present species, although there is nothing in his description to determine the fact. The same thing may be said of the description and figures of Batsch. Rostafinski, in the Monograph, seems to have been satisfied as to the identity of Batsch's materials: in the Appendix, he writes D. serpula, but gives no reason.

Rare. New York. England, France, Germany.

2. DIDYMIUM ANELLUS Morgan.

PLATE XVIII., Fig. 7.

1894. Didymium anellus Morgan, Jour. Cin. Soc., p. 64. 1899. Didymium anellus Morg., Macbr., N. A. S., p. 85. 1911. Didymium anellus Morg., Lister, Mycetozoa, 2nd ed., p. 134.

Plasmodiocarp in small rings or links, then confluent and elongated, irregularly connected together, bent and flexuous, resting on a thin venulose hypothallus, or sometimes globose, the peridium dark colored, with a thin layer of stellate crystals, irregularly ruptured; capillitium of slender, dark-colored threads, which extend from base to wall, more or less branched, and combined into a loose net; columella a thin layer of brown scales; spores globose, very minutely warted, violaceous, 8-9 mu.

This minute species resembles a poorly developed, or sessile, phase of D. melanospermum. Some of the sporangia (?) are spherical; such show a very short dark stalk. The columella is scant, and the spores are smaller than those of D. melanospermum.

Ohio. Reported more recently from Europe and Ceylon.

3. DIDYMIUM WILCZEKII Meylan.

1908. Didymium wilczekii Meyl., Bull. Soc. Vaud. Sci. Nat., XLIV., p. 290. 1911. Didymium wilczekii Meyl., List., Mycetozoa, 2nd ed., p. 134.

Plasmodiocarpous, dehiscing irregularly, columella scant; capillitium abundant, the threads brown, anastomosing, forming an elastic net; spores purple-brown, minutely spinulose, 10-12 mu.

Resembling plasmodiocarpous forms of D. squamulosum, a montane var.; small and delicate, our specimen about 16 x 6 mm. Evidently not common; collected but once by Professor Bethel at an altitude of 11,000 feet, Rocky Mountains of Colorado.

Reported in Switzerland and Sweden.

In certain Swiss gatherings made in 1913 Miss Lister finds capillitial threads with spiral taeniae as in Trichia! (Jour. of Bot., Apr. 1914.) The threads in our specimen are roughened, somewhat as in D. squamulosum, though less strongly; the spores are nearly smooth, fuliginous at first, paler and violaceous when saturate.

4. DIDYMIUM FULVUM Sturgis.

1917. Didymium fulvum Sturgis, Mycologia, IX., p. 37.

Sporangia gregarious, sessile, elongate or forming curved plasmodiocarps, sometimes confluent, rarely sub-globose, concave beneath, pale-raw-umber in color, 0.5-0.8 mm. in diameter, occasionally seated on a concolorous, membranous, lime-encrusted hypothallus which may form pseudo-stalks; sporangium wall membranous, stained with yellow blotches, thickly sprinkled with clusters of large acicular crystals of pale-yellowish lime; columella very much flattened or obsolete; capillitium an abundant network of delicate, almost straight or flexuose, pale-purple or nearly hyaline threads, frequently with dark, calyciform thickenings as in Mucilago, and occasionally showing fusiform, crystalline blisters; spores dark-purplish-brown, coarsely tuberculate, the tubercles usually arranged in curved lines, paler and smoother on one side, 12.5 to 14.5 mu. Colorado.

5. DIDYMIUM CRUSTACEUM Fr.

1829. Didymium crustaceum Fr., Syst. Myc., III., p. 124.

Sporangia closely aggregated, globose, or by compression deformed, sessile, snow-white, by virtue of the remarkably developed covering of calcareous crystals by which each sporangium is surrounded as if to form a crust, the peridium membranous, colorless, usually shrunken above and depressed; columella pale, small, or obsolete; hypothallus scant or vanishing; capillitium of rather stout violaceous threads seldom branched except at the tips, where they are pale and often bifid, or more than once dichotomously divided; spores strongly warted, globose, violet-brown, 10-13 mu.

This species has in some ways all the outward seeming of a diderma, but cannot be referred to that genus because of the crystalline character of its crust. This is a very marked structure; loosely built up of very large crystals, it is necessarily extremely frail, nevertheless persists, arching over at a considerable distance above the peridium proper. Sometimes, however, caducous, evanescent.

The sporangia are said to be sometimes stipitate. This feature does not appear in any of the material before us. Lister in Mycetozoa Pl. XL., c. draws the capillitium much more delicate than it appears in our specimens. The hypothallus is sometimes noticeable under some of the sporangia where closely crowded, but is not a constant feature.

Rostafinski (by typographical error?) confused in the Monograph, pp. 164, 165, this species with Persoon's Physarum confluens. In the Appendix he substitutes the Friesian nomenclature. Persoon's description of his species is insufficient, and throws no light on the problem whatever.

Rare. Iowa; Black Hills, South Dakota. Reported common in Europe. Canada; Vancouver Island to the St. Lawrence.

6. DIDYMIUM SQUAMULOSUM (Alb. & Schw.) Fries.

1805. Diderma squamulosum Alb. & Schw., Consp. Fung., p. 88. 1816. Didymium effusum Link, Diss., II., p. 42. 1829. Didymium squamulosum (Alb. & Schw.), Fries, Syst. Myc., III., p. 118. 1875. Didymium effusum (Link) Rost., Mon., p. 163. 1894. Didymium effusum (Link) List., Mycetozoa, p. 99.

Sporangia, in typical forms, gregarious, globose or depressed-globose, gray or snow-white, stipitate; the peridium a thin iridescent membrane covered more or less richly with minute crystals of lime; the stipe when present, snow-white, fluted or channelled, stout, even; columella white, conspicuous; hypothallus usually small or obsolete; capillitium of delicate branching threads, usually colorless or pallid, sometimes with conspicuous calyciform thickenings; spores violaceous, minutely warted or spinulose, 8-10 mu.

This, one of the most beautiful species in the whole series, is remarkable for the variations which it presents in the fruiting phase. These range all the way from the simplest and plainest kind of a plasmodiocarp with only the most delicate frosting of calcareous crystals up through more or less confluent sessile sporangia to well-defined elegantly stipitate, globose fruits, where the lime is sometimes so abundant as to form deciduous flaky scales. The hypothallus, sometimes entirely wanting, is anon well developed, even continuous, venulose, from stipe to stipe. The capillitium varies much in abundance as in color; when scanty, it is colorless and in every way more delicate, when abundant, darker in color and sometimes with stronger thickenings.

D. fuckelianum Rost., as shown in N. A. F., 2090, and in some private collections, seems to be a rather stout phase of the present species; the stipe is more abundantly and deeply plicate, is sometimes tinged with brown, and the capillitium is darker colored and coarser than in what is here regarded as the type of the species; but withal the specimens certainly fail to meet the requirements of Rostafinski's elaborate description and figure, Mon., p. 161 and Fig. 154.

D. effusum Link, probably stands for a sessile form of this species, but Link's brief description (1816) is antedated by the much better one of Albertini and Schweinitz, l. c.

Generally distributed throughout the wooded regions of North America, from New England to Nicaragua, and from Canada to California. Not uncommon about stable-manure heaps, in flower beds, and on richly manured lands. July, August.

Nicaragua specimens not only show a continuous vein-like hypothallus, but have the peridia often confluent, the columellae in such cases confluent, the stipes distinct. Furthermore, the largest spores reach the limit of 12.5 mu, and perhaps the larger number range from 10-12.5 mu, and all are very rough. This corresponds with D. macrospermum Rost., which is distinguished, says the author (Mon., p. 162, opis), "chiefly by the large and strongly spinulose spores." However, the same sporangium in our Central American specimens yield spores 9.5-12.5 mu, a remarkable range. So that D. macrospermum on this side the ocean, at least, cannot be distinguished from D. squamulosum, as far as spores are concerned. A similar remark may be made relative to the form of the columella which Rostafinski, in his figures especially, would make diagnostic. The columella in the sporangia with largest and roughest spores is that of a perfectly normal D. squamulosum.

7. DIDYMIUM MELANOSPERMUM (Pers.) Macbr.

PLATE VII., Figs. 3, 3 a.

1794. Physarum melanospermum Pers., Roem. N. Mag. Bot., p. 89. 1797. Didymium farinaceum Schrader, Nov. Gen. Pl., p. 26, t. 5, Fig. 6.

Sporangia gregarious, hemispheric, depressed, umbilicate below, stipitate or sessile; the peridium firm, dull brown in color, frosted with minute crystals of lime, breaking irregularly; stipe, when present, short, stout, dull black, opaque, arising from a broad base or hypothallus; columella large, prominent; dark-colored, rough above, concave below; capillitium of more or less sinuous, usually dark-colored threads, sparingly branched, and often with calyciform thickenings; spore-mass black, spores by transmitted light pale, purplish-gray, spinulose or rough, 10-12 mu.

A well-marked and common species, distinguished by its depressed sporangium and dark-colored, opaque stipe. The latter is usually very short, almost completely concealed in the concavity of the umbilicate sporangium. The columella is dark-colored, forming the floor of the peridial cavity.

Persoon first named this species as here. Later on, Uster's Ann., XV., 6, he substituted villosum as a more appropriate specific name. Schrader rejects both names given by Persoon as unsuitable, and suggests farinaceum. Schrad., op. cit., p. 27.

New England, Ohio, Missouri, Alabama, Iowa, Nebraska; Europe; probably cosmopolitan.

8. DIDYMIUM MINUS Lister.

PLATE X., Figs. 4, 4 a, 4 b.

1892. Didymium farinaceum Schr., var. minus, List., Mycetozoa, p. 97. 1896. Didymium minus List., Morg., Jour. Cin. Soc., p. 61. 1899. Didymium minus List., Macbr., N. A. S., p. 89.

Sporangia gregarious, depressed-globose, umbilicate below, whitish or gray, small, about 1/2 mm., stipitate; stipe erect, rather slender, black, faintly striate, about equal to the sporangium in the horizontal diameter; columella distinct, dark brown, globose or depressed-globose, attaining in some cases the centre, rough; capillitium delicate, almost colorless, radiating, sparsely branched; spores in mass dark brown, by transmitted light violet-tinted, minutely roughened, 8-10 mu.

Probably more common than the preceding, and generally mistaken for it. Distinguished by its smaller size, longer and more slender stem, and general trim, well-differentiated appearance. Certainly very near the preceding, of which Mr. Lister regards it as merely a variety. Professor Morgan thought it in this country the more common form.

New York, Ohio, Iowa; reported from Europe, Africa, South America.

9. DIDYMIUM CLAVUS (Alb. & Schw.) Rabenhorst.

1805. Physarum clavus Alb. & Schw., Consp. Fung., p. 96. 1829. Didymium melanopus Fries, Syst. Myc., III., p. 114. 1844. Didymium clavus (Alb. & Schw.) Rabh., Ger. Cr. Fl., No. 2282. 1875. Didymium clavus (Alb. & Schw.) Rost., Mon., p. 153. 1899. Didymium clavus (Alb. & Schw.) Rabenh., Macbr., N. A. S., p. 90. 1911. Didymium clavus Rost., List., Mycet., 2nd ed., p. 128.

Sporangia gregarious, pale gray, discoid or pileate, depressed, stipitate; the peridium dark-colored, frosted with calcareous crystals above, naked below; stipe short, slender, tapering upward, furrowed, arising from a hypothallus more or less distinct, black; columella obsolete; capillitium of delicate threads, pale or colorless, little branched; spores violaceous, pale, nearly smooth, 6-8 mu.

This species is well differentiated, easy of recognition by reason of its peculiar discoid sporangium, calcareous above, naked and black beneath. D. neglectum Massee, reported from Philadelphia, is said to be a slender form of the present species. The figures of D. clavus by Albertini and Schweinitz are excellent, as also the description.

Not common. Pennsylvania, Ohio, Iowa.

10. DIDYMIUM NIGRIPES (Link) Fries.

PLATE VII., Figs. 2, 2 a, 2 b.

1809. Physarum nigripes Link, Obs. Diss., I., p. 27. 1818. Physarum microcarpon Fr., Sym. Gast., p. 23. 1829. Didymium nigripes (Link) Fr., Syst. Myc., III., p. 119. 1875. Didymium microcarpon (Fr.) Rost., Mon., p. 157. 1896. Didymium microcarpon Fr., Morg., Jour. Cin. Soc., p. 61.

Sporangia gregarious, globose or hemispheric, umbilicate beneath, small, white, stipitate; the peridium smoky, covered with minute calcareous crystals; stipe slender, erect, black, opaque; hypothallus scutate, black; columella distinct, globose, black or dark brown; capillitium of delicate threads, pale brown or colorless, with occasional brown thickenings or nodes, sparingly branched; spores pale, violaceous by transmitted light, minutely warted, 6-8 mu.

This is D. microcarpon Rost. Fries, l. c., acknowledges the priority of Link's appellation, and discards microcarpon. Rostafinski adopted microcarpon simply because he thought it more appropriate. Fries describes the columella "none or black." It is doubtful whether we have the typical Friesian form on this continent. The fructification is in our specimens small, about .4 mm., and the spores, as noted by Morgan, small; otherwise the species is hardly more than a variety of the next. Under the name D. nigripes Lister groups our Nos. 10, 11, 12. N. A. F., 1393, represents Dr. Rex's conception of the present species.

Not common. New York, Ohio, Iowa.

11. DIDYMIUM XANTHOPUS (Ditmar) Fr.

PLATE XVI., Fig. 10.

1817. Cionium xanthopus Ditmar, Sturm, Deutsch. Fl., III., p. 37, t. 43. 1829. Didymium xanthopus (Dit.) Fr., Syst. Myc., III., p. 120. 1873. Didymium proximum Berk. & C., Grev., II., p. 52. 1892. Didymium microcarpon (Fr.) Rost., Macbr., Bull. Lab. Nat. Hist. Iowa, II., p. 146, in part. 1894. Didymium nigripes Fr., List., Mycetozoa, p. 98, in part.

Sporangia gregarious, white, globose, slightly umbilicate, stipitate; the peridium thin, and nearly or quite colorless, frosted with crystals of lime; the stipe yellowish or yellowish brown, corneous, erect, subulate, slender; hypothallus none; columella pale or white, turbinate, globose or depressed-globose; capillitium of dull brown, or colorless threads more or less branched, always white at the tips; spores violaceous, nearly smooth, 7.5-8.5 mu.

This seems to be the most common form in the United States. It is distinguished from the preceding by the longer, more delicate, generally orange-yellow, stem with pale or white columella. The spores also average a shade larger. N. A. F., 412 and 2089, are illustrations of D. xanthopus. The columella in blown-out specimens is very striking, well confirming the diagnosis of Fries, "valde prominens, globosa, stipitata, alba." Berkeley makes the color of the capillitium diagnostic of D. proximum, but this feature is insufficient.

Eastern United States; common.

12. DIDYMIUM EXIMIUM Peck.

PLATE XVI., Figs. 11, 11 a, 11 b.

1879. Didymium eximium Peck, Rep. N. Y. Mus., XXXI., p. 41.

Sporangia scattered, dull grayish-yellow or gray, depressed-globose, umbilicate, minute, stipitate; the peridium comparatively thick, tenacious, especially persistent below, tawny or yellow; the stipe pale brown or orange, erect, even or slightly enlarged at base; hypothallus scant or none; columella prominent, more or less discoidal, rough, or spinulose, especially on the upper surface, yellow; capillitium not abundant, pale fuliginous, often branching and anastomosing so as to form a loose net; spores nearly smooth, dark violaceous by transmitted light, 8.5-9.5 mu.

The species differs from D. xanthopus in several particulars,—in the much firmer, more persistent, and less calcareous peridium, in the more complex capillitium, in the darker and larger spores, and especially in the peculiar and prominent columella, which is not only rough, but even "sometimes spinulose even to the extent of long spicules penetrating to one-third the height of the sporangia." N. A. F., 2493.

As stated under No. 8, these last two species are called varieties only of D. nigripes. They are so retained in Mycetozoa, 2nd ed. Since, however, they are the usual presentation of the species in the United States, it seems wise to let them stand for the present, as here. They are quite distinguishable; D. eximium especially well marked.

Apparently rare, it yet ranges from New York to eastern Iowa, in colonies rather large. Okoboji Lake;—fine!

13. DIDYMIUM TROCHUS List.

1898. Didymium trochus List., Jour. Bot., XXXVI., p. 164.

Sporangia plasmodiocarpous, hemispherical or turbinate, white, sessile or very short-stalked, cream-colored or white; peridium double, the outer shell-like, the inner membranaceous, more or less adherent to the outer, both caducous together, leaving the thickened base surrounding an expanded columella; stipe, when present, very short, stout; capillitium colorless, nearly simple; spores brownish-purple, strongly warted, 9-10 mu.

On decaying leaves, rotten cactus, yucca, etc., Monrovia, California; Bethel.

Reported from England on beds of leaves or straw; in Portugal Dr. Torrend finds it on or in dead leaves of Agave americana! Evidently an American species, and belonging to arid regions; its occurrence in England surprising!

14. DIDYMIUM ANNULATUM Macbr. n. s.

PLATE XX., Figs. 4, 4 a.

Sporangia small, scattered, annulate, not only without columella but perforate when the stipe is broken, umbilicate above and below, grey, coated with crystalline frustules, opening irregularly about the periphery; stipe white, or pallid, fluted, tapering upward from a distinct hypothallus; capillitium scanty consisting of delicate, sparsely branching threads, the branchlets anastomosing more or less at length, attached to the peridial wall, radiating from the rim of the slightly depressed top of stipe, without special thickenings save at the insertion of the ramules a triangular enlargement is usual and of dark or pallid shade; spores smooth; however they show three or four spots on the hemisphere and other minute but variable markings; 9-10 mu. Seattle, Washington.

Differs from D. nigripes in color of the stipes, capillitium, spore-diameter, etc.

15. DIDYMIUM DUBIUM Rost.

1875. Didymium dubium Rost., Mon., p. 152. 1892. Didymium listeri Mass., Mon., p. 244. 1894. Didymium dubium Rost., List., Mycetozoa, p. 95. 1911. Didymium dubium Rost., List., Mycetozoa, 2nd ed., p. 126.

Fructification wholly plasmodiocarpous, snow-white, small, 2-6 mm., flat and thin; the outer wall double, membranous within, calcareous-crystalline without; columella none; capillitium simple of rather thick, vertical, brown threads, sparingly united laterally, and only occasionally furcate at the ends, especially above; spores minutely spinulescent, violaceous pale, 12-15 mu.

Massee thought English specimens out of harmony with the original description and gave them a new name. To refuse this, Lister enlarges the range of spore-measurements and disregards some of Rostafinski's specifications as to capillitium. Our specimens are as described.

Bohemia. England. Shores of Lake Okoboji, Iowa.

This is indeed a doubtful form. It differs from D. difforme chiefly in that the outer calcareous shell is not smooth, but is covered with abundant loose crystals, frosted. The spores are paler but about the same size. The frosting may be incident to local climatic conditions at the time and place of desiccation.

16. DIDYMIUM DIFFORME Duby.

1797. Diderma difforme Pers. Tentamen Disp. Meth., p. 19. 1830. Didymium difforme Duby., Bot. Gall., ii., p. 858. 1875. Chondrioderma difforme Pers., Rost., Mon., p. 177. 1894. Didymium difforme Duby., List., Mycetozoa, p. 94. 1899. Diderma personii Macbr., N. A. S., p. 96. 1911. Didymium difforme Duby., List., Mycetozoa, 2nd ed., p. 124.

Plasmodiocarpous, the smooth, white outer peridium separable from the thin, colorless or purplish inner layer; capillitium of rather coarse, flat, dichotomously branching threads, broader below; spores minutely warted, or almost smooth, dark brown, 12-14 mu.

The white crust-like outer wall has more than once carried this species into Diderma. It is still doubtful whether we are here dealing with Chondrioderma calcareum Rost. Miss Lister cites a variety, S. difforme comatum, with more abundant capillitium which may represent Rostafinski's species.

Evidently rare in the United States; reported more common in Europe and eastward. In our specimens the crust-like outer peridium shows crystals on the broken edge only; the body of the object, as its outer surface seems to be amorphous.

17. DIDYMIUM QUITENSE (Pat.) Torr.

1895. Chondrioderma quitense Pat., Bull. Soc. Myc. Fr., XI., p. 212. 1909. Didymium quitense (Pat.) Torr., Flor. Myxom., p. 150. 1911. Didymium quitense Torr., List., Mycetozoa, 2nd ed., p. 126. 1913. Didymium quitense (Pat.) Torr., Sturg., Myx., Col. II., p. 446.

Sporangia more or less plasmodiocarpous, scattered, depressed, white; the outer peridium distinct, crust-like, remote from the thin membranous inner wall; columella undefined; capillitium brown, much branched, forming a network especially outwardly; spores very dark violaceous-brown, rough with a tendency to obscure reticulation; 12-14 mu.

This species is different from D. difforme chiefly in the rougher and somewhat banded epispore. It is reported from Ecuador by Father Torrend, and from Colorado mountains by Dr. Sturgis to whose kindness I am indebted for the specimens here described. Evidently a high mountain species.

Colorado.

18a. DIDYMIUM ANOMALUM Sturg.

PLATE XIX., Figs. 13 and 13 a.

1913. Didymium anomalum Sturg. Myxomycetes of Col., II., p. 444

Sporangia in the form of very thin effused grey plasmodiocarps, 2-10 cm. long, 1 mm. or less in thickness. Wall single or membranous, hyaline or yellowish, with rather scanty deposits of small, stellately crystalline or amorphous lime. Columella none. Capillitium consisting entirely of straight membranous, tubular, columns, extending from the base to the upper wall of the plasmodiocarp, 7-22 mu thick and usually containing small crystalline masses of lime. Spores bright violet-brown, minutely and irregularly spinulose, 10-11.5 mu diam.

Hab. on the inner bark of Populus. Colorado Springs, Colo., July 1911.

Our specimens by the courtesy of Dr. Sturgis.

EXTRA-LIMITAL

18. DIDYMIUM INTERMEDIUM Schroeter.

1896. Didymium intermedium Schroet., Hedwigia, Vol. XXXV., p. 209. 1902. Didymium excelsum Jahn, Ber. Deut. Bot. Ges., XX., p. 275.

Sporangia clustered or gregarious, discoidal and umbilicate below, or lobed or convolute, greyish white, stipitate; stipe pale yellow, tapering upwards, stuffed with lime crystals, expanding into the yellowish, discoidal, recurving columella; capillitium colorless, more or less branching; spores dark purple-brown, irregularly reticulate, 9-12 mu.

Differs from D. squamulosum in the reticulate epispore. Brazil.

19. DIDYMIUM LEONINUM Berk. & Br.

1873. Didymium leoninum Berk. & Br., Jour. Linn. Soc., XIV., p. 83. 1876. Lepidoderma tigrinum Rost., App. to Mon., p. 23. 1909. Lepidodermopsis leoninus v. Hoehnel, Sitz. K. Ak. Wiss. Wien, Math. Nat. Ks., CXVIII., 439.

Sporangia gregarious, sub-globose, covered more or less completely with white or yellowish deposits of crystalline lime, stipitate; stipes short, orange or brown, containing lime, enlarged to form the globose orange columella and often connected at base by a venulose hypothallus; capillitium of slender threads, anastomosing, colorless at the tips; spores violet-grey, minutely warted, 7-9 mu.

Like Lepidoderma tigrinum, but has different calcic crystals.

Java and Ceylon.

3. Diderma Persoon

1794. Diderma Persoon, Roem. N. Mag. Bot., I., p. 89. 1873. Chondrioderma Rost. Versuch, p. 13, Mon., p. 167. 1894. Chondrioderma Rost., List., Mycetozoa, p. 75. 1899. Diderma Persoon, Macbr., N. A. S., p. 92.

Sporangia plasmodiocarpous or distinct, sessile or stipitate; the peridium as a rule double, the outer wall generally calcareous with the lime granules globular, non-crystalline, the inner wall very delicate and often, in the mature fructification, remote from the outer; columella generally prominent.

The genus Diderma is usually easy of recognition, by reason of its double wall, the outer, crustaceous, usually calcareous, and its limits remain substantially as originally set by Persoon. His definition is as follows:—

"Peridium ut plurimum duplex; exterius fragile; interius pellucens, subdistans. Columella magna, subrotunda. Fila parca latentia."—Syn. Meth. Fung., p. 168.

Rostafinski changed the name of the genus to Chondrioderma (chondri, cartilage), seemingly at De Bary's suggestion, and seems to have regarded Persoon's definition as applicable to those species only in which the wall is not only plainly double, but in which the two walls are as plainly remote from each other. More especially he esteemed a new generic name necessary, since he regarded several included species, as D. spumarioides, D. michelii, etc., monodermic.

Since it is doubtful whether any diderma is really monodermic, and since Persoon's definition in any case seems sufficiently elastic, we have seen no reason to discard the older name. Persoon's Diderma when established, l. c., included D. floriforme. He made some confusion in his later work by admitting some physarums. This induced Schrader to throw all the didermas into his new genus, Didymium.

According to the nature of the sporangial wall, the species fall rather naturally into two sections:—

A. Outer sporangial wall distinctly calcareous, fragile; species generally sessile Diderma

B. Outer sporangial wall cartilaginous, the inner less distinct, or concrete with the outer; species oftener stipitate Leangium

A. Sub-Genus DIDERMA

1. Fructification wholly plasmodiocarpous 1. D. effusum

2. Fructification of distinct sporangia.

a. Sporangia on a common hypothallus.

O Outer wall fragile, not widely remote from the inner 2. D. spumarioides

OO Inner wall lacking 3. D. simplex

OOO Outer wall crustaceous, porcelain-like.

i. Spores 8-10 4. D. globosum

ii. Spores 12-15 5. D. crustaceum

OOOO Outer wall firm, not crustaceous 6. D. lyallii

b. Sporangia isolated, or, at least, not on a common hypothallus, sessile.

O Outer wall porcellanous, roseate 7. D. testaceum

OO Outer wall white 8. D. niveum

OOO Outer wall ashen 9. D. cinereum

c. Sporangia stipitate 10. D. hemisphericum

B. Sub-Genus LEANGIUM

1. Sporangia generally sessile.

a. Inner peridium distinct.

O Membranous colorless, columella scant 11. D. sauteri

OO Colorless, columella prominent, red 12. D. cor-rubrum

OOO Outer ochraceous, inner yellow 13. D. ochraceum

b. Peridial layers inseparable.

O Peridium multifid; columella small or none 16. D. trevelyani

OO Peridium breaking into but few irregular lobes; columella prominent.

i. Peridium umber brown 14. D. roanense

ii. Peridium ashen 15. D. radiatum

iii. Peridium chocolate without, inside white 17. D. asteroides

2. Sporangia stipitate.

a. Peridium pallid, smooth 18. D. floriforme

b. Peridium white, rugulose 19. D. rugosum

1. DIDERMA EFFUSUM (Schw.) Morgan.

1831. Physarum effusum Schw., N. A. F., p. 257. 1896. Diderma effusum (Schw.) Morg., Jour. Cin. Soc., p. 71. 1899. Diderma effusum (Schw.) Morg., Macbr., N. A. S., p. 94. 1899. Diderma reticulatum Rost., Macbr., N. A. S., p. 95. 1911. Diderma effusum Morg., Lister, Mycetozoa, 2nd ed., p. 102.

Fructification plasmodiocarpous, reticulate, creeping, applanate and generally widely effused, white; the peridium thin, cinereous, covered by a delicate, white, calcareous crust; the columella simply the base of the plasmodiocarp, thin alutaceous; the capillitium pale, consisting of short threads somewhat branched toward their distal extremities; spores smooth, pale violaceous, 8-10 mu.

This is Physarum effusum Schw., vid. N. A. F., No. 2297. It is reported by Morgan from Ohio, and we have one specimen from eastern Nebraska, so that it is probably of general distribution in the eastern United States.

This species was in the previous edition distinguished from the Rostafinskian P. reticulatum with spores a little smaller, 6-8 mu, and with a much stronger tendency to the formation of definite sporangia, elongate indeed and branching but often globose or depressed globose. This we may know as,

VAR. RETICULATUM Rost.

1875. Chondrioderma reticulatum Rost., Mon., p. 170. 1894. Diderma reticulatum (Rost.) Morg., Jour. Cin. Soc., p. 71.

Sporangia gregarious, generally rounded, not much depressed, flat, sometimes, especially toward the margin of a colony, elongate, venulose or somewhat plasmodiocarpous, dull white, the inner peridium ashen or bluish, remote from the calcareous crust, which is extremely fragile, easily shelling off; columella indistinguishable from the base of the sporangium, thin, alutaceous; capillitium of short, generally colorless, delicate, sparingly branching or anastomosing threads perpendicular to the columella; spores black in mass, by transmitted light violet-tinted, smooth, 6-8 mu.

Perhaps our most common form. Found in fall on dead twigs, leaves, etc. Recognized by its rather large, white, depressed or flattened sporangia tending to form reticulations, and hence suggesting the name. The lines of fruiting tend to follow the venation of the supporting leaf; where the sporangium is round, the columella is a distinct rounded or cake-like body; where the fruit is venulose, the columella is less distinct.

By these rounded forms we pass easily, as by a gate, to D. hemisphericum, which, when wholly sessile, differs still in greater diameter of the sporangia and in having somewhat larger spores. Usually in such case the compared colony will show somewhere a very short and stout but very real stipe supporting the discoid fruit.

Rostafinski divided the genus Chondrioderma, i. e. Diderma, into three sections:—

Monoderma to include those species in which the calcareous crust is less distinct or connate with the true peridium.

Diderma, in which the two structures were plainly separate.

Leangium, used as in the present work. In his first section Rostafinski placed C. reticulatum and C. michelii; in the second, C. difforme and C. calcareum.

Lister has examined Rostafinski's type of C. reticulatum and declares that it has the usual didermic characters. Hence there is no doubt that our small-spored American specimens are covered by Rostafinski's description, No. 72. On the other hand, Lister makes C. difforme (Pers.) Rost. a Didymium, by its crystalline coat. That species therefore is removed from consideration in this connection. C. calcareum remains as applicable to American forms having the spores 10-12 mu, but according to the author of the species the capillitium is abundant and definitive. Unhappily the type of C. calcareum is lost (Lister, Mon., p. 95), so that there is no other means of verification than the description and Rostafinski's figure. Under these circumstances we consider the name calcareum inapplicable to any American forms we have so far seen. See next species. As to the American species which have been distributed as C. calcareum (Lk.) Rost., they are, so far as seen, referable to D. reticulatum (Rost.), Morg. Here also belongs No. 1217, Ellis, N. A. F.

New York, Pennsylvania, Ohio, Iowa, Nebraska. Probably to be found throughout the eastern United States.

2. DIDERMA SPUMARIOIDES Fries.

1829. Diderma spumarioides Fries, Syst. Myc., III., p. 104. 1833. Physarum stromateum Link., Handb., III., p. 409. 1876. Chondrioderma stromateum (Lk.) Rost., App., p. 18.

Sporangia sessile, crowded, spherical, or by mutual pressure irregular, white; the peridium plainly double, but the layers adhering, the outer more strongly calcareous, but very frail, almost farinaceous; hypothallus more or less plainly in evidence, white or pale alutaceous; columella distinct, though often small, globose, yellowish; capillitium variable in quantity, sometimes abundant, brown, somewhat branching and anastomosing outwardly, the tips paler; spores minutely roughened, dark violaceous, about 10 mu.

This species has the outward seeming of a didymium, but is plainly different as that genus is here defined, since the calcareous crust, although inclined to be pulverulent, is made up of minute granules, not crystals, of lime. The hypothallus is sometimes hardly discoverable, anon well developed, out-spread, rugulose, far beyond the limits of the fructification. In his Monograph, p. 175, Rostafinski includes here Physarum stromateum Link. In the Appendix he is inclined to raise Link's form to the dignity of a distinct species, basing the diagnosis upon the superposition of the sporangia in certain cases, a feature entirely unknown to Link's description and of extremely uncertain value, since by their crowding the sporangia are liable always to be pushed above each other. We therefore regard C. stromateum (Link) Rost. as a synonym of the present species, as the description, Link, Handb., III., 409, indicates, so far as it goes.

3. DIDERMA SIMPLEX (Schroet.) Lister.

1885. Chondrioderma simplex Schroet., Krypt. Fl. Schles., III., 1, p. 123. 1911. Diderma simplex List., Mycetozoa, 2nd ed., p. 107.

"Plasmodium bright yellowish brown." Sporangia gregarious, sessile, globose or depressed globose, .3-.5 mm., or anon plasmodiocarpous, brown or brick-red when fresh, becoming paler, ochraceous, etc.; hypothallus everywhere in evidence; columella ill-defined; capillitium scanty, the threads delicate, pale, branching as they join the peridial wall; spores dull violaceous, slightly roughened, 8-10 mu.

A rather crude, primitive representative of this beautiful genus. The inner peridium seems to be lacking,—a comfort to Rostafinski! Rare. Our best specimens are from New Jersey, by courtesy of Dr. C. L. Shear. These went to fruit on leaves and branches of Vaccinium. It seems to affect the heather of Europe, moorland, etc. I have also specimens from the herbarium of the lamented Dr. Rex. These are more plasmodiocarpous, but open beautifully by a median fissure as in Physarum sinuosum Bull. In no American gathering that I have examined does the capillitium show calcareous thickenings as described by the British text.

4. DIDERMA GLOBOSUM Persoon.

PLATE VII., Figs. 5, 5 a.

1794. Diderma globosum Pers., Roem. N. Mag. Bot., I., p. 89. 1875. Chondrioderma globosum (Pers.) Rost., Mon., p. 180.

Sporangia more or less closely gregarious, sessile, globose or by mutual pressure prismatic or polyhedral, white, the outer wall smooth, polished, crustaceous, fragile, far remote from the inner, which is thin, smooth, or rugulose, iridescent blue; hypothallus usually pronounced and spreading beyond the sporangia, sometimes scanty or lacking, columella variable, sometimes very small, inconspicuous, sometimes large, globose, ellipsoidal, even pedicellate; capillitium abundant, brown or purplish brown, branching and occasionally anastomosing to form a loosely constructed superficial net; spores globose, delicately spinulose, 8 mu.

This species seems rare in this country. We have specimens from Iowa. It is distinguished by small spores and generally snow-white color. Lister has thrown doubt upon Rostafinski's definition of this form—Mycetozoa, p. 78. Almost everything distributed in the United States under this name belongs in the next species. Reported also from Ohio,—Morgan. Washington. But:—it should be found in Europe, where first described!

There are two ways to meet the difficulty. In the first place it seems probable that a small-spored form really hides somewhere in Europe. The difference between the Monograph measurement and the size admitted for D. crustaceum Pk., evidently considered by Mr. Lister as type and so used in his illustration, Pl. 85, is too great to be esteemed merely an error. That added .3 (Rost.) indicates caution, the average of several measurements. Our D. globosum may represent what the Monograph describes.[32] In the second place we may as American students mistake larger and more globular forms of something else, of D. spumarioides Fr., whose spores are but little larger; or of D. effusum (Schw.) Morg., where the flattened plasmodiocarps anon splatter out to globose drops of polished whiteness, and whose spores are 8 mu. But even here the chances of error are small. In the species last named the columella or sporangial base is alutaceous, not white; in Fries' species, while the columella if present may be white, the peridial walls are different, difficult to distinguish.

For these reasons, D. globosum Pers. may stand, waiting further light from Europe.

5. DIDERMA CRUSTACEUM Peck.

PLATE VII., Fig. 7

1871. Diderma crustaceum Peck, Rep. N. Y. Mus., XXVI., p. 74. 1889. Chondrioderma crustaceum (Peck) Berl., Sacc., VII., p. 373.

Plasmodium at first watery, colorless, becoming at length milky white; sporangia closely crowded or superimposed, in a cushion-like colony, creamy white, globose, imbedded in the substance of the hypothallus, the outer peridium smooth, delicate, crustaceous, fragile, remote from the blue iridescent inner membrane; hypothallus prominent; columella variable, generally present, globose; capillitium dark-colored, the threads branching and combining to form a loose net; spore-mass black, spores by transmitted light dark violaceous, delicately roughened, 12-15 mu.

Common. Readily to be distinguished from the preceding by the larger spores and more crowded habit. New England west to Nebraska.

The didermas are generally delicately beautiful. The outer wall in the present species is like finest unglazed china, softly smooth, and yet not polished, often absolutely white, with porcellanous fracture. An inter-parietal space separates the outer from the inner wall, so that the former may be broken, bit by bit, without in the least disturbing the underlying structure. The inner wall is ashen or gauzy iridescent green, sending back all colors in reflected light. The spores are violet, deeply so when fresh, the capillitium strong and likewise tinted; the columella passing down and blending with the common snow-white hypothalline base. The distinct habits of the two species are represented in Figs. 5 and 7. In the one the distinct sporangia are associated but not crowded; in the other all are massed together in quite aethalioid fashion, forming circumambient, chalky masses of considerable size, 2 or 3 cm., overcrowded, superimposed, where the sporangia are regular in shape and size by reason of mutual pressure. The plasmodium develops in forests and orchards, among decaying leaves, but is inclined to rise as maturity draws near, to ascend some twig erect, or the stem of a living plant to the height of several inches where the sporangia at length appear "heaped and pent", an encircling sheath, conspicuous after the fashion of a spumaria for which it is indeed sometimes mistaken.

6. DIDERMA LYALLII (Massee) Macbr.

PLATE XVIII., Figs. 5 and 5 a

1892. Chondrioderma lyallii Massee, Mon., p. 201. 1894. Chondrioderma lyallii Mass., List., Mycetozoa, p. 81. 1899. Diderma lyallii Mass., Macbr., N. A. S., p. 99. 1911. Diderma lyallii List., sub-species, Mycetozoa, 2nd ed., p. 105.

Sporangia obovate, more or less closely crowded, white, stipitate, about 1 mm. in diameter, the outer peridium firm, stout, encrusted, especially above, with granular masses of lime, the inner well developed, more or less cartilaginous, opaque, yellow or buff-colored; hypothallus well developed, venulose, white, passing up unchanged to form the short, stout stipe and lower outer peridium; columella prominent, half the height of the sporangium, brown; capillitium of short, brown threads, rigid, much branched, forming a net, widened irregularly and especially at the net-nodes; spore-mass black, spores by transmitted light bright brown, rough, 15-17 mu.

A very distinct species; large, fine, showy sporangia in more or less crowded clusters spring from a snow-white, common hypothallus. First reported from western Canada. Our first specimens were collected by the late Mr. Charles Irish, on the eastern slopes of the Sierras, in Nevada; now coming in abundantly from all the western mountains to the Pacific.

7. DIDERMA TESTACEUM (Schrad.) Pers.

PLATE VII., 4, 4 a, and 4 b.

1797. Didymium testaceum Schrad., Nov. Gen. Plant., p. 25. 1801. Diderma testaceum Persoon, Syn., p. 167. 1873. Chondrioderma testaceum (Schrad.) Rost., Vers., p. 13. 1874. Diderma mariae-wilsoni Clinton, Rep. N. Y. Mus., XXVI., p. 74. 1899. Diderma testaceum (Schrad.) Pers., Macbr., N. A. S., p. 99. 1911. Diderma testaceum Pers., List., Mycetozoa, 2nd ed., p. 106.

Sporangia gregarious, sessile, depressed-spherical or sometimes elongate, small, 1 mm. or less, rose-white, smooth, the outer peridium crustaceous, rather thick and persistent, polished, slightly raised above the inner, which is dull ashen and more or less wrinkled; hypothallus none; columella prominent, hemispherical in the typical rounded forms, slightly rough, reddish or reddish alutaceous; capillitium usually abundant, of slender, delicate pale or colorless threads, little branched, and smooth; spores violaceous-brown, minutely roughened, 8-9 mu.

A very beautiful species occurring at the same time as the preceding and in similar situations. All our specimens from the west are on dead leaves of oak; some eastern gatherings are on moss. Easily recognized when fresh by its delicate pink or roseate color; weathered specimens are white, and might be confused with forms of D. reticulatum, but the sporangia in the present species are less flattened and only rarely in special situations run off to linear or plasmodiocarpous shapes characteristic of D. reticulatum.

Not common, although widely distributed from east to west. New England, New York, New Jersey, South Carolina, Ohio, Illinois, Iowa, Nebraska, California (Harkness), Washington, Oregon.

8. DIDERMA NIVEUM (Rostafinski) Macbr.

PLATE XVIII., Fig. 11 and 11 a

1875. Chondrioderma niveum Rost, Mon., p. 170. 1877. Diderma albescens Phillips, Grev., V., p. 114.

Sporangia gregarious, scattered, or more often crowded, sessile, depressed-spherical, sometimes ellipsoidal or elongate, white, the outer peridium crustaceous, chalky, smooth and fragile, the inner distinct, delicate, ochraceous; hypothallus scant or none; columella well developed, globose or hemispherical, orange-tinted or ochraceous; capillitium abundant, made of threads of two sorts, some purplish or dusky, with pale extremities, uneven, others more delicate and colorless, and with wart-like thickenings, all sparingly branched; spores violet-brown, minutely roughened, 9-10 mu.

This species is not common. From Colorado we have fine specimens typical in every way. Specimens from Washington are flat so far as at present at hand; probably represent D. deplanatum (R.) List., which the last named author regards as varietal of the present species, entering it and D. lyallii as sub-species 2 and 1 respectively. D. deplanatum may perhaps be best so disposed of; but D. lyallii is distinguished at sight, as well as by microscopic characters, spores nearly twice as great, rougher and different in color.

9. DIDERMA CINEREUM Morg.

1894. Diderma cinereum Morg., Myx. Mi. Val., p. 70.

Sporangia gregarious, more or less crowded or even confluent, sub-globose, only slightly depressed, ashen white; the peridium not obviously double, very smooth and thin, rupturing irregularly; hypothallus an indistinct membrane or wholly wanting; columella large, globose or hemispheric, white, the surface granulose; capillitium of very slender colored threads, the extremities pellucid, more or less branched; spores violaceous, minutely warted, 9-11 mu.

Growing on old wood, leaves, etc. The sporangium .3-.5 mm., thin and smooth or rugulose. This elegant little species I know only from specimens received from Mr. Morgan. It seems to be closely related to D. spumarioides, from which it is distinguished by its color, darker, and its smoother, or less spinulose spores. The author compares the color and external appearance to that of P. cinereum,—Jour. Cin. Soc., XVI., p. 154.

Ohio, Pennsylvania.

10. DIDERMA HEMISPHERICUM (Bull.) Horne.

1791. Reticularia hemispherica Bull., Cham. de Fr., I., p. 93. 1829. Didymium hemisphericum (Bull.) Fr., Syst. Myc., III., p. 115. 1829. Diderma hemisphericum (Bull.) Horne., Fl. Dan., XI., p. 18. 1832. Didymium michelii Lib., Pl. Ard., No. 180. 1873. Chondrioderma michelii (Lib.) Rost., Fuckel, Sym. Myc., p. 74.

Sporangia gregarious, orbicular, discoid, depressed above and often umbilicate below, stipitate or sometimes sessile, the outer peridium white, fragile, crustaceous, soon breaking about the margins, closely applied to the inner, which is delicate, cinereous, and ruptures irregularly; stipe about equal to the diameter of the sporangium, 1 mm., rather stout, calcareous but colored, brownish or alutaceous, more or less wrinkled longitudinally, the wrinkles when present forming veins on the lower surface of the sporangium; hypothallus small; columella not distinct from the thickened brownish or reddish base of the sporangium; capillitium of delicate threads, mostly simple and colorless, often scanty; spores pale violaceous, nearly smooth, 8-9 mu.

A very well marked species, easily recognized, at least when stipitate, by its remarkable discoid or lenticular sporangia. After the spore-dispersal, the stipes are long-persistent, surmounted by a peculiar disk representing the consolidated columella, lower sporangial wall, and expanded stem-top. Sessile specimens are like similar forms of D. reticulatum, but in all the gatherings before us the stipitate type is at hand to reveal the identity of the species.

Rostafinski's figures, 131, 146, 149, and 150, adapted from Corda, exaggerate the hypothallus, but otherwise leave nothing to be desired.

As to synonymy, Bulliard has plainly the priority. His figure, t. 446, Fig. 1, can refer to nothing else, especially reenforced as it is by Sowerby, Eng. Fung., t. 12.

Rather rare on fallen stems of herbaceous plants, but widely distributed, New England to Oregon and Washington.

11. DIDERMA SAUTERI (Rost.) Macbr.

1875. Chondrioderma sauteri Rost., Mon., p. 181. 1891. Chondrioderma aculeatum Rex, Proc. Phil. Acad., p. 390.

Sporangia scattered, gregarious, sessile, lenticular or hemispherical, flattened above and sometimes concave or umbilicate below, dusky or yellowish white, the outer peridium papyraceous, thin, occasionally wrinkled, rupturing irregularly, remote from the inner, which is thin, delicate, semi-transparent, grayish, rarely iridescent; hypothallus none; columella irregular, sometimes small and hardly evident, rugose, with spine-like processes, the persisting bases of the capillitial threads, reddish brown; capillitium scanty, white, or colorless, simple or sparingly branched; spores dark violaceous, spinulose, 12-13 mu.

This is Chondrioderma aculeatum Rex, Proc. Acad. Nat. Sci. Phil., 1891, p. 390. After careful comparison of specimens and various descriptions, especially that of Rostafinski with the type specimens of Dr. Rex, I am constrained to concur with Lister in adopting Rostafinski's name. The sporangia in the type specimens (Rex) are on moss, borne at the extreme tips of acuminate or aculeate leaves, so that at first sight they appear stipitate.

Apparently rare. Maine, New York.

12. DIDERMA COR-RUBRUM Macbr. n. s.

PLATE XVIII., Fig. 2

Sporangia gregarious clustered, small .5-.7 mm., sessile corrugate-plicate, especially above, snow-white, the outer peridium cartilaginous polished without and within, the inner delicate, evanescent; columella well developed, globose or clavate, anchored by several stout transverse trabeculae to the peridial wall, papillate, deep-red as is the peridium especially below; capillitium very delicate, sparingly branching, colorless; spores verruculose, fuliginous tinged with red, about 12 mu.

This curious but elegant little species is represented by a single colony collected by Professor Morton Peck in Iowa. It resembles D. sauteri but is distinguished by the plicate white wall, the stout columella with its lateral extensions, as by the more delicate spores. On rotten wood.

13. DIDERMA OCHRACEUM Hoffm.

1795. Diderma ochraceum Hoffm., Deutsch. Fl. Tab. 9, 2, b. 1911. Diderma ochraceum Hoffm., List., Mycetozoa, 2nd ed., p. 109.

Sporangia gregarious or clustered, .7-1 mm., sessile, globose or sometimes plasmodiocarpous, ochraceous yellow; outer wall cartilaginous with yellow deposits of lime, the inner also yellow, adherent or free; columella not distinct; capillitium simple or branching, purple-brown, hyaline at base; spores spinulose, purplish-grey, 9-11 mu.

Mr. Lister reports this species from Massachusetts.

14. DIDERMA ROANENSE (Rex) Macbr.

1893. Chondrioderma roanense Rex, Proc. Phil. Acad., p. 368.

Sporangia scattered, discoidal, thin, flattened or slightly convex above, plane or plano-concave below, umber-brown, stipitate, the outer peridium smooth, brittle, rupturing irregularly, the basal fragments somewhat persistent, concrete with the inner peridium, which is pure white, except near the columella, and punctate; stipe short, variable, longitudinally ridged, jet-black; hypothallus none; columella flat, discoidal, pale ochraceous; capillitium sparse, white or colorless, composed of simple, rarely forked, sinuous threads occasionally joined by lateral branches; spores dark violaceous, distinctly warted, 12-14 mu.

This species is readily distinguished by its color. The sporangia, found on rotten wood, are large, 1 mm., brown, and have thick, persistent walls. Dr. Rex considered that the species differs from other related forms not only in color, but in the well-marked discoidal columella and the jet-black irregular stipe. It is perhaps most nearly related to the following species.

Tennessee.

15. DIDERMA RADIATUM (Linn.) Morg.

PLATE XVIII., Fig. 8

1753. Lycoperdon radiatum Linn. (?) Sp. Pl., 1654. 1797. Didymium stellare Schrad., Nov. Gen. Pl., p. 21. 1801. Diderma stellare (Schrad.) Persoon, Syn., p. 164. 1875. Chondrioderma radiatum (Linn.) Rost., Mon., p. 182. 1894. Diderma radiatum (Linn.) Morg., Jour. Cin. Soc., p. 66. 1899. Diderma stellare Schrad., Macbr., N. A. S., p 104. 1911. Diderma radiatum List., Mycetozoa, 2nd ed., p. 112.

Sporangia scattered, depressed-globose, sometimes also flattened below, stipitate, smooth or slightly corrugate, ashen or brownish, about 1 mm. in diameter, the peridium dehiscing irregularly or somewhat radiately from above downwards, the segments reflexed, the inner layer not distinguishable, or inseparable; stipe short, stout, brownish, sometimes almost lacking; hypothallus not conspicuous, but sometimes sufficient to connect the bases of adjacent stipes; columella large, hemispherical or globose, pallid or yellowish; capillitium abundant, of slender generally simple, colored threads, paler at the furcate tips; spores dark violaceous, minutely roughened, 8-11 mu.

Rare on rotten logs in the forests; September. Easily recognized by the short-stiped, ashen sporangia which before dehiscence indicate by delicate tracings the lines which subsequent cleavage is to follow. In texture the peridium resembles that of D. floriforme.

Pennsylvania, Ohio, Iowa, Virginia, Colorado, Washington, Oregon; Europe generally.

The Linnaean description on which to base the specific name D. radiatum is wholly inadequate. It appears also by the testimony of Linne fils, that L. radiatum Linne is a lichen! and the name is so applied by Persoon. But in the Linnaean herbarium preserved at London, teste Lister, the original type of Lycoperdon radiatum L. may yet be seen! to the confusion of fils, Persoon, and other followers of Schrader all, and our stellar species becomes radiate now, let us hope for long!

16. DIDERMA TREVELYANI (Grev.) Fr.

1825. Leangium trevelyani Grev., Scot., Cr. Fl., Tab. 132. 1829. Diderma trevelyani (Grev.) Fr., Syst. Myc., III., p. 105. 1875. Chondrioderma trevelyani (Grev.) Rost., Mon., p. 182. 1877. Diderma geasteroides Phill., Grev., V., p. 113. 1877. Diderma laciniatum Phill., Grev., V., p. 113.

Sporangia scattered, globose or nearly so, smooth or verruculose, reddish-brown or rufescent, sessile or short-stipitate, the outer peridium firm, splitting more or less regularly into unequal, revolute, petal-like lobes which are white within, the inner not distinguishable as such; stipe, when present, equal, furrowed, concolorous; columella small or none; capillitium abundant, the threads rather rigid, purple or purplish brown, branching and anastomosing, more or less beaded; spores dark, violaceous brown, spinulose, 10-13 mu.

In 1876, Harkness and Moore collected in the Sierra Nevada Mountains of California, forms of Diderma which are described by Phillips, Grev., V., p. 113, as D. geasteroides and D. laciniatum. English authorities who have examined the material agree that the forms described constitute but a single species, and Lister makes them identical with D. trevelyani (Grev.) Fr. Rostafinski's figures, 161, 162, are a curious reproduction, evidently, of Fried. Nees von Esenbeck's, Plate IX., Fig. 4. Massee describes a columella; Lister says there is none. What may occasion such divergence of statement none may say; such forms as come in so far from our western mountains have no columella.

17. DIDERMA ASTEROIDES List.

PLATE XVIII., Figs. 3, 3 a

1902. Diderma asteroides List., Jour. Bot., XL, p. 209. 1911. Diderma asteroides List., Mycetozoa, 2nd ed., p. 113.

Sporangia globose or ovoid-globose, the apex more or less acuminate, sessile, sometimes narrowed at the base to a short, thick stalk, brown or chocolate tinted, marked at the apex by radiant lines, and at length dehiscent by many reflexing lobes revealing the snow-white adherent inner peridium on the exposed or upper side; columella also white, globose or depressed-globose; capillitium generally colorless, somewhat branched, especially above; spores dark violaceous, verruculose, 10-12 mu.

Oregon, the Three Sisters Mountains; Colorado; California.

A very beautiful species, recognizable at sight; when unopened, by the peculiar chocolate brown, the sporangia smaller than in D. radiatum. When opened, the snow-white flower-like figure, flat against the substratum, is definitive. Very near number 16 preceding; the dehiscence more regular.

18. DIDERMA FLORIFORME (Bull.) Pers.

PLATE VIII., Figs. 1, 1 a, 1 b.

1791. Sphaerocarpus floriformis Bulliard, Champ., p. 142, t. 371. 1794. Diderma floriforme (Bull.) Persoon, Roem. N. Mag. Bot., p. 89.

Sporangia crowded, generally in dense colonies, globose, smooth, ochraceous-white, stipitate, the peridium thick, cartilaginous, splitting from above into several petal-like lobes, which become speedily reflexed exposing the swarthy spore-mass, the inner peridium not discoverable, inseparable; stipe concolorous, about equal to the sporangium; hypothallus, generally well developed, but thin, membranaceous, common to all the sporangia; columella prominent, globose or cylindric, often constricted below, and prolonged upward almost to the top of the spore-case; capillitium of slender, delicate, sparingly branched threads; spores dark violaceous-brown, studded with scattered warts, 10-11 mu.

Not uncommon, especially on rotten oak logs. Easily recognized by the peculiar form of the fruit, spherical before dehiscence, floriform after. Unlike most species, this form often fruits in dark places, in the interior of a log, even in the ground.

New England, Ontario to Iowa and Nebraska, and south.

19. DIDERMA RUGOSUM (Rex) Macbr.

PLATE XVIII., Fig. 10.

1893. Chondrioderma rugosum Rex, Proc. Phil. Acad., p. 369.

Sporangia gregarious, scattered, white or ashen, rugulose over the whole surface, the ridges marking the lines of subsequent rupture or dehiscence, the peridium thin papyraceous, stipitate; stipe well developed about equal to the sporangium, subulate, almost black; hypothallus none; columella distinct, generally white, sometimes small, globose, sometimes penetrating the sporangium, to one-half the height; capillitium white or colorless, the filaments freely forked and combined by lateral branches into a loose network attached to the columella and basal wall below and the upper sporangial wall above; spores violaceous-brown, warted, 8-10 mu.

This species is well designated rugosum, and is recognizable at sight by its wrinkled, areolate surface. Related to D. radiatum in the prefigured dehiscence, but otherwise very distinct. Liable to be overlooked as a prematurely dried physarum. Rare. Plasmodium gray.

North Carolina, Iowa.

4. Lepidoderma DeBary

1858. Lepidoderma DeBy., MS. Rost., Versuch, p. 13.

Sporangia stalked or sessile; peridium cartilaginous, adorned without with large calcareous scales, superficial or shut in lenticular cavities; capillitium non-calcareous.[33]

Key to Species of Lepidoderma

A. Sporangia stipitate, stipe brown 1. L. tigrinum

B. Sporangia sessile, plasmodiocarpous, spores 10-12 mu 2. L. carestianum

C. Sporangia plasmodiocarpous, spores 8-10 mu 3. L. chailletii

1. LEPIDODERMA TIGRINUM (Schrad.) Rost.

PLATE XIV., Fig. 7.

1797. Didymium tigrinum Schrad., Nov. Gen. Plantarum, p. 22. 1873. Lepidoderma tigrinum (Schrad.) Rost., Versuch, p. 13.

Sporangia scattered, rather large, hemispherical-depressed, stipitate, umbilicate beneath, the peridium shining, olivaceous or purplish, tough, covered more or less abundantly with angular scales; the stipe stout, furrowed, dark brown, but containing calcareous deposits withal, tapering upward, and continued within the peridium as a pronounced more or less calcareous columella; hypothallus more or less prominent, yellowish or brownish; capillitium dark, purplish-brown, of sparingly branching threads radiating from the columella; spores dull purplish-brown, minutely roughened, 10-12 mu.

A singular species, rare, but easily recognized by its peculiar, placoid scales, large and firmly embedded in the peridial wall. The internal structure is essentially that of Diderma or Didymium. The species occurs in hilly or mountainous regions, on moss-covered logs. The plasmodium pale yellow, some part of it not infrequently remains as a venulose hypothallus connecting such sporangia as are near together.

New England to Washington and Oregon; Vancouver Island.

2. LEPIDODERMA CARESTIANUM (Rabenh.) Rost.

1862. Reticularia carestiana Rabenh., MS. Fung. Eur. exsic., No. 436. 1875. Lepidoderma carestianum (Rabenh.) Rost., Mon., p. 188. 1891. Amaurochaete minor Sacc. & Ell., Mich., II., p. 566.

Fructification in the form of flat, pulvinate plasmodiocarps, or, anon, sporangiate, the sporangia sessile, sub-globose, ellipsoidal, elongate, irregular, confluent, yellowish-grey, the peridium covered more or less completely with dull white, crystals or crystal-like scales; columella, where visible, yellowish-brown, calcareous; capillitium, coarse, rigid, more or less branched and united, or colorless, delicate, forming a definite net; spores distinctly warted, purple 10-12 mu.

This is a most remarkable species. The sporangiate forms little resemble those distinctly plasmodiocarpal. In the former the calcic scales and crystals are distinct and quite as in L. tigrinum; in the latter they are cuboid, irregular. The wall of the peridium in the plasmodiocarps at hand is black, and the covering accordingly shows white; in the sporangial forms the wall is brown, and the scales have a yellow tinge as if tinged with iron. In the sporangial presentation the capillitium is intricate delicate; in the plasmodiocarp, rigid, dark-colored, etc. This looks like a didymium and in so far justifies the opinion of earlier students. Fries, of course, includes all these things with the didymiums, and D. squamulosum probably often sheltered them under extended wing.

Didymium granuliferum Phill., Grev., V., p. 114, from California is by European authors referred here. The capillitium carries calcareous crystalline deposits in special vesicles and the spores show remarkable variation in unusual size—15-30 mu.[1]

Should probably be entered Lepidoderma granuliferum (Phill.) Fr., spores 15-18 mu.[34]

Utah,—Harkness.

3. LEPIDODERMA CHAILLETII Rost.

PLATE XVIII., Figs. 6, 6 a, 6 b.

Sporangia distinct, coalescent or plasmodiocarpous, large, when isolated 1-1.5 mm., dull drab in color, very sparsely sprinkled with white tetrahedral or irregular scales; the peridium thin, more or less translucent, rugulose, dull brown, persistent; columella none; capillitium abundant, under the lens purple-brown, sparingly branched, even, stout, rigid, no calcareous deposits nor vesicles; spores 8-10 mu, minutely warted, fuliginous.

Yosemite Canyon, California, Prof. B. Shimek.

This is, no doubt, similar to L. carestianum but differs in the size and habit of the sporangia, and in the fact that the capillitium is uniform throughout, whatever the style of fructification, and in the size, color, and surface characters of the spore.

Evidently not Didymium granuliferum Phill. Both will, no doubt, be again collected, and we shall then have much needed light.

Nor is this quite Rostafinski's species as cited. The spores are much smaller; Rostafinski says 10-12 or more, and calls for a distinctly netted capillitium, the surface strongly marked by abundant calcareous crystals. Ours may be a different thing.

5. Colloderma G. Lister

1910. Colloderma, Jour. of Botany, XLVIII., p. 312.

Peridium double; the outer gelatinous, the inner membranaceous; capillitium intricate, limeless.

COLLODERMA OCULATUM (Lipp.) G. Lister.

1894. Didymium oculatum Lipp., Verh. Zo-Bot. Ges. Wien, XLIV., p. 74. 1910. Colloderma oculatum (Lipp.) G. List., Jour. Bot., XLVIII., p. 312.

Sporangia gregarious, globose, or sub-globose, sessile or short-stipitate, olivaceous or purplish-brown, smooth and shining, the outer peridium gelatinous, thickened by moisture, hyaline; stipe dark brown; columella none; capillitium as in Didymium purplish-brown, colorless at the tips; spores spinulose, fuscous, about 12 mu.

New Hampshire, Europe.

Our specimens from the late Dr. W. G. Farlow who collected it in New Hampshire. Swollen by immersion in water the sporangia take on an eye-like appearance, oculate, etc.

EXTRA-LIMITAL

PHYSARINA von Hoehnel.

1909. Physarina von Hoehnel, Akad. Wiss. Wien; Math-nat. KL., CXVIII., p. 431.

Sporangium wall rough with blunt spine-like processes, otherwise as Diderma.

One species, op. cit., p. 432, P. echinocephala v. Hoehn.

Java. Might as well be called Diderma echinocephalum, one would think. Structure is that of Leangium. The striking character is a surface modification of the outer peridium, according to the description.

ORDER II

STEMONITALES

Capillitium present, thread-like, arising in typical cases from a well-developed columella; spores in mass, black or violet-brown, more rarely ferruginous.

Key to the Families of Stemonitales

A. Fructification aethalioid, capillitium poorly defined; columella rudimentary or none AMAUROCHAETACEAE

B. Fructification of distinct sporangia, capillitium well defined; the columella generally prominent, long and abundantly branched throughout STEMONITACEAE

C. Sporangia distinct; capillitium developed chiefly or only, from the summit of the columella LAMPRODERMACEAE

A. AMAUROCHAETACEAE

Fructification aethalioid, an inch or two in diameter, in form varying with the habitat and place; capillitium dendroid, consisting of rather stout branches which rise irregularly more or less vertically from the hypothallus, branch repeatedly, often anastomose to form a network, especially toward the periphery; spores black.

A single genus—

1. Amaurochaete Rostafinski

1873. Amaurochaete Rost., Versuch., p. 8.

The genus Amaurochaete as defined by Rostafinski and the genus Reticularia as represented by R. lycoperdon Bull. stand, the expression, perhaps, of not dissimilar histories. Whether in regressive or progressive series, each to-day presents a case of arrested development. Each in aethalioid fructification, reveals a mass of involved individual (?) sporangia, so imperfectly developed that their outlines can be inferred rather than anywhere, with absolute definiteness, certainly ascertained. Perhaps, because similar sporangia in the group to which either belongs, do come under other circumstances, to more perfect individual form and function—perhaps for this reason we may look upon these aethalia as exhibiting a suspended performance; the sporangia have failed to go forward to what was evidently a possible, though apparently not an essential destiny in form and figure. For the care and dispersal of the spores, achievement must surely be somewhat impaired. Whatever the measure of such inefficiency, among the Stemonitales Amaurochaete shows the acme, as Reticularia among the brown-spored forms.

In Amaurochaete the individuality of anything like separate sporangia is less clear. The view afforded, however, by a good vertical section of a well-developed colony or cushion is interestingly arborescent. Ragged, dendroid stems arise, dissipated above into a network most intricate, a "pleached arbor" if you please. The resemblance of the overhead net to that presented by a stemonitis or comatricha is very striking.

Key to the Species of Amaurochaete

A. Capillitium rigid, irregular spores rough 1. A. fuliginosa B. Capillitium soft, woolly, cincinnate, spores as in A 2. A. tubulina

1. AMAUROCHAETE FULIGINOSA (Sowerby) Macbr.

PLATE V., Figs. 8, 8 a.

1803. Lycoperdon fuliginosum Sow., Eng. Fung., t. 257. 1805. Lycogala atrum, Alb. & Schw., Consp. Fung., p. 83. 1875. Amaurochaete atra (Alb. & Schw.) Rost., Mon., p. 211.

Fructification aethalioid, varying in form and size, if on the upper side of the substratum, pulvinate, if below pendent and almost stipitate, covered with a delicate cortex, at first shining, soon dull, black, fragile, and early dissipated; hypothallus long-persisting, supporting the capillitium, which is extremely variable, irregular, and for its perfection dependent upon the form assumed by the aethalium, and the conditions of weather, etc., under which it matures, sometimes, especially when prostrate, in a very much depressed aethalium, spreading into long fibrous threads, again under better conditions rising in columella-like forms, supporting a peripheral net; spores dark brown or black, irregularly globose, spinulose, 12.5-15 mu.

Common in Europe, and probably not uncommon in this country wherever pine forests occur. Specimens before us are from New England and New York, Ohio, Carolina, Colorado. Canada.

Sowerby, in his comment on plate 257, Eng. Fungi, says: "It appears to consist of branching threads affixed to the deal and holding a dense mass of sooty powder. Over the whole is a thin, deciduous pellicle." This description seems to be applicable to nothing else. The figure amounts to little. Fries recognizes the English description, as does Rostafinski, but both authors adopt the later name given by Albertini and Schweinitz, simply because of the excellent detailed description found in the Conspectus.

2. AMAUROCHAETE TUBULINA (Alb. & Schw.) Macbr.

PLATE XX., 6 and 6 a.

1805. Stemonitis tubulina (Alb. & Schw.), Cons. Fung., p. 102. 1825. Lachnobolus cribrosus Fr., Syst. Orb. Veg., p. 14. 1912. Amaurochaete cribrosa (Fr.) Macbr., Com. in litt. to Herbaria, Harvard, etc.[35] 1917. Amaurochaete cribrosa (Fr.) Sturg., G. Lister, Jour. Bot., LVIII, p. 109.

Plasmodium at first transparent then white then rosy, ashen or grey finally deepening to jet-black; the aethalium even, thin, variable in extent from one to ten centimeters, covered by a distinct but thin transparent cortex, papillate, extended laterally but a short distance beyond the fructification, fragile, soon disappearing; hypothallus long-persistent, thin, silvery, supporting the capillitium as if by stipes, short slender columns, irregular plates, expansions, etc.; the capillitium an intricate network, very abundant, elastic, on fall of the peridium appearing like tiny tufts of wool, the meshes large, but formed as in Stemonitis, persistent, dull black; spores, under the lens, dull olivaceous black, minutely roughened, 12-14 mu.

This species differs from the preceding, already well known, especially in the capillitial characters. In the older species the capillitial branches fray out, and are only sparingly united into a net extremely lax. In the present form the net is the thing, common to all sporangia. The total effect is to lend to the blown-out aethalium a woolly appearance, entirely unlike that of its congener under the same conditions. But until fructification is quite mature, the presence of the collaborating sporangia below is indicated, suggested, by the papillose upper surface.

The amaurochetes are remarkable in that they appear upon coniferous wood, logs or lumber, to all appearance undecayed. The species just described developed abundantly in August on the recently decorticated logs of Pinus ponderosa, on the south-western slopes of Mt. Rainier, Washington. In logging operations in the locality referred to, the trees are felled often at considerable distance from the mill. They are not infrequently large, 75-120 cm. in diameter. The logs are dragged along the ground, the transportation facilitated by removal of the bark from the new fallen trunk. In a few weeks' time, affected by alternate rain and sun, the whole surface becomes marked with hundreds of minute, almost invisible cracks, and it is in the larger of these that the plasmodium of the present species has its habitat. Hardly any mycologic phenomenon is more surprising than to see plasmodia rising to fructification, scores at a time, upon a surface, new and white, showing otherwise no evidence of any decomposition. Doubtless the persisting cambium, the unused starches, sugars, the wood of the season yet unlignified, afford easily accessible nutrition.

When this form was first examined in the laboratory its distinctness was immediately seen. It was without doubt Fries' cribrose reticularia; nobody questions that. Under this name, citing Fries' description, specimens were sent out to herbaria as Harvard. Further study of the records, however, soon convinces one familiar with the ontogeny of the case that we are here face to face with the species, described by Alb. & Schw. in their fine Conspectus. Their account of the form, evidently often taken and now described with great care, is entirely clear when read in presence of the facts. It is here submitted, as less easy of access but essential, if the reader would appreciate the present disposal of the species.

"S. Tubulina NOBIS

"S. magna pulvinata subhemisphaerica, stylidiis gregariis circinantibus, capillitiis elongatis cylindraceis in massam pulveraceam fuscam connatis, apicibus obtusis, prominulis, lucidis nigris.

"The size indeed, the circumscribed form, the capillitiums conjoined into a single body—indue this (form) with an appearance peculiar to a degree; however, should anyone prefer to call it a very remarkable variety of the preceding (S. fasciculata), we shall not strenuously refuse. At first glance it looks like a tubulina. After the fashion of its kind, the beginning is soft and milky. The diameter generally an inch and a half to two inches, the height four to six lines; the form perfectly round, or more rarely somewhat oblong. The hypothallus, stout, pellucid silvery, betimes iridescent, when turned to the light, easily separable from the substratum, bears the columellae, dusky, thin, hair-like, aggregate and yet entirely free, and everywhere circinately convergent, depressed by the superimposed burden, hence decumbent: ... the capillitium loosely interwoven, coalesces to a common mass whose smooth and shining surface shows above, regularly disposed minute papillae, the apices of individual sporangia.

"Far from infrequent, on decorticate pine, of Lycogala atrum a constant companion"!

It goes of course without saying, that for the authors quoted, Lycogala atrum is Amaurochaete atra Rost. A. fuliginosa (Sow.) of more recent students, described and perfectly figured in the volume cited.

It is surprising that they did not enter the present species also as a lycogala. But the stemonitis relationship this time impressed them rather than the aethalial; besides they were misled by the S. fasciculata of Gmelin and Persoon, a composite which the genius of Fries hardly availed to disentangle twenty-five years later.

The last named author, as we see, wrote first Lachnobolus, then Reticularia. He calls the interwoven capillitium—lachne, wool, a "pilam tactu eximie elasticam," etc. He read the description in the Conspectus, but carried away the stemonitis suggestion dominant there, as we have seen, put S. tubulina A. & S. as an undeveloped phase of S. fusca, which, of course, it is not. It needed not the authority of Rostafinski, Mon., p. 197, to assure us this. The earlier authors describe the species in course of development to complete maturity, and clinch the story by declaring the form a constant companion of the commonly recognized amaurochete, so fixing the relationship for us by habitat also.

These men made a mistake, of course, in placing their species among the stemonites at all. They did much better however than Fries who called it a reticularia. It was also a mistake to cite S. fasciculata,—the small fasciculate tufts of S. fusca and S. axifera offering by the aggregate habit only faint resemblance,—a possible refuge for those who would prefer another disposition of their species distinct (aliena) though it is.

Since Fries' day the species has been overlooked although the genus has received more than once attention. Zukal Hedwigia, XXXV., p. 335, describes A. speciosa as a new species. This Saccardo writes down, Syll. Fung., VII., p. 399, S. tubulina A. & S., admitting, however, at the same time, that as fine an authority as Raciborsky refuses to call Zukal's species either a stemonite or an amaurochete, thinks it deserving generic appellation of its own.

However, A. speciosa Zuk. need not here concern us. Neither in his description nor figures does Zukal at all approach the form we study. His species is not an amaurochete; the size of the spores suggest that, to say nothing of the capillitial structure.

In the same volume VII., the distinguished author introduces another amaurochete, A. minor Sacc. & Ellis, Mich. II., p. 566. This is American; sent from Utah by our famous pioneer collector Harkness. A specimen is before us: it is a lepidoderma! in shining, scaly armor dressed; vid. under L. carestianum.

Since the distribution of Washington material, as mentioned, our species reappears at various points in western Europe, points in England, etc., and will no doubt now share, hereafter as a century ago, the habitat so long conceded to the long familiar older type.

B. STEMONITACEAE

Capillitium abundant, springing usually as dissipating branches from all parts of the columella; the sporangia generally definite and distinct, though sometimes closely placed and generally rising from a common hypothallus.

Key to the Genera of the Stemonitaceae

A. Fructification aethalioid; capillitium charged with vesicles 1. Brefeldia

B. Sporangia distinct, or nearly so.

a. Stipe and columella jet-black.

1. Capillitium so united as to form a surface net 2. Stemonitis

2. Capillitial branch-tips free 3. Comatricha

b. Stipe and columella whitish; calcareous 4. Diachaea

1. Brefeldia Rostafinski

1873. Brefeldia Rost., Versuch, p. 8.

Sporangia occupying in the aethalium several layers, those of the median, and especially of the lowest layers, furnished with columellae which blend beneath; capillitium threads in the lowest layers arising from the columella, in the upper extending radiately between the individual sporangia, and united at the sporangial limits by means of rather large inflated sacs.

The genus Brefeldia is, like some others, difficult to dispose of in any scheme of classification where linear sequence must be followed. Rostafinski placed it in an order by itself. Its relationships are on the one hand with Amaurochaete and Reticularia, and on the other with the Stemonitales, though easily distinguished from either. It is intermediate to Amaurochaete and Stemonitis, and withal, as it appears to us, a little nearer the latter, as the limits of the individual sporangia are in Brefeldia pretty well defined.

1. BREFELDIA MAXIMA (Fr.) Rost.

PLATE V., Figs. 7, 7 a, 7 b, and PLATES XXI., XXII.

1825. Reticularia maxima Fries, Syst. Orb. Veg., I., p. 147. 1875. Brefeldia maxima (Fr.) Rost., Versuch., p. 8.

Aethalium large, four to twenty cm, papillate above, violet-black at first, then purple or purple-brown, developed upon a widespread, silver-shining hypothallus; sporangia in favorable cases distinct, indicated above by the papillae; columellae obscure, black; capillitium abundant, the threads uniting by multifid ends to surround as with a net the peculiar vesicles; spore-mass dark violet-black, the individual spores paler by transmitted light, distinctly papillose, 12-15 mu.

A very remarkable species and one of the largest, rivalled by Fuligo only. To be compared with Reticularia, which it resembles somewhat externally, and with some of the larger specimens of Enteridium. The plasmodium at first white with a bluish tinge is developed abundantly in rotten wood, preferably a large oak stump, and changes color as maturity comes on, much in the fashion of Stemonitis splendens, leaving a widespread hypothallic film to extend far around the perfected fruit-mass. In well-matured aethalia, "Jove favente," the sporangia stand out perfectly distinct, particularly above and around the margins. Closely and compactly crowded, they become prismatic by mutual pressure, and attain sometimes the height of half an inch or more. In the centre of the fructification, next the hypothallus, the sporangia are very imperfectly differentiated. Many are here horizontally placed, and perhaps supplied with an imperfectly formed peridium,—if so are to be interpreted the lowest parts of the capillitial structure, the long, branching, ribbon-like strands which lie along the hypothallus. Some of these branch repeatedly with flat anastomosing branchlets, ultimately fray out into lengthened threads, and perish after all the superstructure has been blown away. From every part of the structure so described, but more especially from the margins, are given off in profusion the strange cystiferous threads, so characteristic of this genus. These are exceeding delicate filaments, attached at one end, it may be, to a principal branch, at the other free or united to a second which again joins a third, and so looping and branching, dividing, they form a more or less extended network, a capillitium in which are entangled the myriad spores. Each filament bears at its middle point (or is it the meeting point of two?) a peculiar plexus which embraces several large cysts or vesicles whose function or further homology does not readily appear.

From the base of the fructification rise also ascending branches which are black, terete, and not infrequently branched as if to form the capillitium of a stemonitis. These ascending branches are in many cases, probably in all, real, though as yet imperfectly developed, columellae. They rise, at least in many cases, directly from the hypothallus, each is central to an individual sporangium, rises to about two-thirds its height, but never attains the summit. The sporangia are so crowded that many are choked off below, never reach the top of the aethalium. In such cases the columella may cease at the sporangium-top. The columella bears cystiferous threads sparingly, if at all; nevertheless these abound in the peripheral portions of the sporangium all the way up, and are especially noticeable beyond the level of the top of the columella. Many are so arranged that the plexus with its vesicles occupies a place in the plane separating adjacent sporangia, suggesting the possibility that we have here to do with an imperfectly developed surface-net and peridium. In this view the cysts would represent the meeting-point of two opposite radial capillitial threads rather than the middle of one. This accords with Rostafinski's observations and drawings. The cysts, then, belong morphologically to the peridium or sporangium wall. It is a stemonitis whose sporangia have never been perfectly differentiated, a case of arrested development. See further under Stemonitis confluens.