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

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

Rare. On mossy logs, Maine.

3. Physarum (Persoon) Rost.

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

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

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

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