Chapter IV: LEPIDODERMA, DeB. Sporangium stipitate or sessile, sometimes

plasmodiocarp; the wall a thin, firm, colorless membrane, with an outer layer of large scales consisting of bicarbonate of lime, the scales either lying upon the wall or inclosed in lenticular cavities of the membrane. Stipe present or absent; the columella usually conspicuous. Capillitium of very slender threads, simple or outwardly branching at a sharp angle, connected at the extremities. Spores globose, violaceous.

"In the present genus the carbonate of lime is present in the form of very minute amorphous lumps until near to maturity, when it is dissolved and reappears as bicarbonate of lime deposited in comparatively large flakes."--_Massee._

1. LEPIDODERMA TIGRINUM, Schr. Sporangium large, much depressed, hemispheric or lenticular, the base umbilicate, stipitate; the wall a firm, dark colored membrane, variegated with large and small irregular shining scales, greenish-yellow or straw color, rupturing irregularly. Stipe stout, thick, erect, rugulose, ochraceous or ferruginous, variable in length, expanding at the base into a thin hypothallus; the columella brown, convex or hemispheric. Capillitium of slender, dark colored threads, simple or sparingly branched, radiating from the columella to the wall. Spores globose, minutely warted, dark violaceous, 10-13 mic. in diameter.

Growing on old wood, moss, etc. Sporangium 1-1.5 mm. in diameter, the stipe 1 mm. or less in length. This appears to be the only species of the genus thus far discovered in this country.

EXPLANATION OF PLATE XII.

Fig. 37.--Didymium proximum, B. & C. _a._ Sporangium and stipe × 33. _b._ Section through the columella.

Fig. 38.--Didymium eximium, Peck. _a._ Showing the rough columella of one form. _b._ Section through the discoid columella of the very much depressed form. Magnified by 33.

Fig. 39.--Didymium minus, Lister. _a._ Sporangium and stipe × 33. _b._ _c._ _d._ Sections through the columella showing different forms.

Fig. 40.--Didymium farinaceum, Schr. Section through the columella. After Rostafinski.

Fig. 41.--Didymium anellus, Morgan, _a._ Growing upon a leaf × 3. _b._ Plasmodiocarp × 17.

Fig. 42.--Spumaria alba, Bull. Var. 1. didymium, sporangia × 3. Drawn from a foreign specimen.

Fig. 43.--Spumaria alba, Bull. _a._ Æthalium natural size. _b._ Capillitium and spores as seen by a magnifying power of 500 diameters.

Fig. 44.--Diderma floriforme, Bull. Stipe and columella × 20.

Fig. 45.--Diderma crustaceum, Peck. _a._ Sporangia crowded on the thick hypothallus, natural size. _b._ Sporangia × 11. _c._ Section through outer coat, inner membrane, and columella.

Fig. 46.--Diderma cinereum, Morgan, _a._ Sporangia growing on a leaf × 3. _b._ Sporangia × 23. _c._ Section through the wall and columella.

Fig. 47.--Diderma reticulatum, Rost. Plasmodiocarp growing on leaf × 3.

Fig. 48.--Diderma effusum, Schw. Plasmodiocarp effused on a leaf × 3.

VOL. XVI. PLATE XII.]

* * * * *

Reprint from THE JOURNAL OF THE CINCINNATI SOCIETY OF NATURAL HISTORY, August, 1896.

THE MYXOMYCETES OF THE MIAMI VALLEY, OHIO.

BY A. P. MORGAN.

Fourth Paper.

(Read May 6, 1896.)

ORDER VIII. PHYSARACEÆ.

Sporangia simple and stipitate or sessile, sometimes plasmodiocarp, rarely combined into an aethalium; the wall a thin membrane, usually with an outer layer of minute roundish granules of lime. Stipe present or often wanting, seldom prolonged within the sporangium as a columella. Capillitium consisting of slender tubules, which branch repeatedly in every direction and anastomose to form an intricate network, the extremities attached on all sides to the wall of the sporangium; the tubules more or less expanded at the angles of the network and inclosing minute roundish granules of lime, these granules either aggregated into nodules with intervening empty spaces or more rarely distributed throughout their entire length. Spores globose, very rarely ellipsoidal, violaceous.

This order is at once distinguished from the Didymiaceæ by the presence of the granules of lime in the capillitium.

TABLE OF GENERA OF PHYSARACEÆ.

I. Tubules of the capillitium having the granules of lime in them aggregated into roundish or angular nodules, with intervening empty spaces.

_A. Outer surface of the sporangium destitute of lime._

1. ANGIORIDIUM. Plasmodiocarp laterally compressed, splitting regularly into two valves.

2. CIENKOWSKIA. Plasmodiocarp terete, elongated, irregularly dehiscent.

3. LEOCARPUS. Sporangia subglobose or obovoid, stipitate or sessile.

_B. Outer surface of the sporangium invested with granules of lime._

_a. Stipe prolonged within the sporangium as a columella._

4. PHYSARELLA. Sporangium oblong, stipitate, the apex re-entrant.

5. CYTIDIUM. Sporangium globose, stipitate, the apex convex.

_b. Stipe never entering the sporangium._

6. CRATERIUM. Sporangium obovoid to cylindric, stipitate.

7. PHYSARUM. Sporangium globose, depressed globose or irregular, stipitate or sessile.

8. FULIGO. Aethalium a compound plasmodiocarp.

II. Tubules of the capillitium with the granules of lime in them distributed throughout their entire length.

9. BADHAMIA. Stipe not prolonged within the sporangium as a columella.

10. SCYPHIUM. Stipe entering the sporangium and prolonged within it as a columella.