The Myxomycetes of the Miami Valley, Ohio Part 6

long, others more than 100 mic. in length.

_B. Spores minutely warted._

5. OLIGONEMA FULVUM, Morgan n. sp. Sporangia rather large, subglobose, sessile, closely crowded and more or less irregular; the wall tawny yellow, very thin and fragile, smooth, shining and iridescent. Ma.s.s of capillitium and spores tawny yellow; elaters simple or sometimes branched, mostly very short, 4 mic. in thickness, sometimes with thicker swollen portions; the surface marked with low smooth spirals, in places faint and obsolete; the extremities rounded and obtuse, usually with a very minute apiculus, 1-3 mic. in length. Spores globose, minutely warted, 10-13 mic. in diameter.

Growing on an old effused Sphaeria. Sporangia .6-.8 mm. in diameter, the elaters mostly 40-80 mic. in length, rarely much longer and sometimes shorter; the longer elaters and those that are branched often arise from confluence of the shorter ones.

EXPLANATION OF PLATE I.

Fig. 13.--Perichaena depressa, Lib.

Fig. 14.--Ophiotheca Wrightii, B. & C.

Fig. 15.--Lachn.o.bolus globosus, Schw.

Fig. 16.--Arcyria Cookei, Ma.s.see.

Fig. 17.--Arcyria minor, Schw.

Fig. 18.--Heterotrichia Gabriellae, Ma.s.see. (After Ma.s.see.)

Fig. 19.--Hemiarcyria plumosa, Morgan.

Fig. 20.--Hemiarcyria funalis, Morgan.

Fig. 21.--Calonema aureum, Morgan.

Fig. 22.--Trichia fallax, Pers.

Fig. 23.--Trichia scabra, Rost.

Fig. 24.--Oligonema flavidum, Peck.

NOTE.--Each figure exhibits the sporangium as it appears magnified about 100 diameters, and the capillitium and spores magnified about 500 diameters.

[Ill.u.s.tration: The Journal of the Cin. Soc. Natural History.

VOL. XVI. PLATE I.]

THE MYXOMYCETES OF THE MIAMI VALLEY, OHIO.

BY A. P. MORGAN.

Third Paper.

(Read February 6, 1894.)

ORDER VI. STEMONITACEae.

Sporangia globose or ovoid to oblong and cylindrical, stipitate; the wall very thin and fragile, soon disappearing. Stipe tapering upward and continued within the sporangium as a more or less elongated columella.

Capillitium of slender brown threads, arising from numerous points of the columella, repeatedly branching and usually anastomosing to form a network, persistent and rigidly preserving the outline of the sporangium. Spores globose, brown or violaceous.

This order is readily distinguished by the brown persistent capillitium, arising from a lengthened columella, and rigidly maintaining the form of the sporangium.

Table of Genera of Stemonitaceae.

_A. Stipe and columella brown or black._

_a. The columella scarcely reaching the center of the sporangium._

1. CLASTODERMA. Threads of the capillitium forking several times, but not combined into a network.

2. LAMPRODERMA. Threads of the capillitium branching and anastomosing to form a network.

_b. The columella extending beyond the center of the sporangium._

3. COMATRICHA. Threads of the capillitium forming only an interior network, attaining the wall by numerous more or less elongated free extremities.

4. STEMONITIS. Threads of the capillitium forming an interior network of large meshes and a superficial network of smaller meshes.

5. ENERTHENEMA. Threads of the capillitium pendent from a discoid membrane at the apex of the columella.

_B. Stipe and columella white or yellowish._

6. DIACHAEA. Threads of the capillitium branching and anastomosing to form a network.

I. CLASTODERMA, Blytt. Sporangium regular, globose, stipitate; the wall very thin and fragile. Stipe elongated, tapering upward, entering the sporangium as a very short or nearly obsolete columella. Capillitium arising by a few branches from the apex of the columella, these branches forking several times at a sharp angle, but not combined into a network, the ultimate branchlets long and free, or only connected together at their tips by persistent fragments of the sporangial wall. Spores globose, violaceous.

The claim of this genus to be distinguished from Lamproderma must rest upon the fact that the branchlets of the capillitium do not anastomose and form a network. It is the same as the genus Orthotricha of Wingate.

1. CLASTODERMA DE BARYANUM, Blytt. Sporangium very small, globose; the wall early disappearing, except the minute fragments which persist at the extremities of the capillitium, and a narrow collar at the base of the columella. Stipe very long, thick and brown below, tapering upward to a pellucid oblong swelling, thence abruptly narrowed to the apex; the columella extremely short, capillitium of very slender pale-brown semi-pellucid threads, divergently forking, the ultimate branchlets often joined 2-4 together at their tips by fragments of the sporangial wall. Spores globose, even, violaceous, 8-9 mic. in diameter. See Plate XI, Fig. 25.

Growing in rather a scattered way on old rotten wood. Sporangium .20-.25 mm. in diameter, the stipe .7-1.3 mm. long. _Orthotricha microcephala_, Wingate. Blytt's species was found in Norway, Wingate's in Pennsylvania; I have met with it several times in this locality. It is possibly more common than it appears, as by reason of the difficulty of seeing the minute sporangium it is pa.s.sed by as some mold. Blytt's spore measurements are 9.5-11 mic.; in some specimens I have seen a few spores of this size, but they are abnormal.

II. LAMPRODERMA, Rost. Sporangia regular, globose, stipitate; the wall thin and fragile, rugulose, shining with metallic tints, breaking up irregularly and gradually falling away. Stipe more or less elongated, smooth, brown or black in color, arising from a hypothallus, tapering upward and entering the sporangium as a short columella scarcely reaching the center. Capillitium of numerous threads radiating from the columella, usually forking several times and combined into a net by lateral anastomosing branchlets. Spores globose, brown or violaceous.

Lamproderma is distinguished by the shining metallic tints of the sporangial wall, and by the short columella scarcely reaching half the height of the sporangium.

1. LAMPRODERMA PHYSAROIDES, A. & S. Sporangium globose; the wall with a silvery metallic l.u.s.ter, at length breaking up and falling away. Stipe long, slender, brown or blackish, arising from a small circular hypothallus; columella clavate, obtuse, not reaching the center of the sporangium. Capillitium of brownish-violet threads, arising from the upper part of the columella; these branch repeatedly at a sharp angle, form an intricate network of elongated meshes, terminating at the wall in numerous short free branchlets. Spores globose, minutely warted, bright brown, 12-14 mic. in diameter.