The general plan of structure corresponds very well with Fries' idea of his genus Tilmadoche, although the present species would seem, by very grossness, strangely out of place with the tilmadoches. But the singular, didermoid, evenly branching, threads of the capillitium, bearing their slender spindle-shaped burdens of lime are very suggestive; it is a diderma gone wandering into the camp of the physarums if one may judge from Miss Lister's graphic plate.
The specific name selected for this peculiar form has once before done service, but apparently for something quite dissimilar. Schumacher, Enum. Pl. Saell. II., p. 199, has P. luteo-album. Fries thinks he had a perichæna on hand; at any rate, not a physarum, and makes Schumacher's combination a synonym for Perichaena quercina Fr., which Rostafinski in turn makes synonymous with P. corticalis (Batsch) R. If "once a synonym always a synonym" be esteemed good taxonomic law, this species must one day have another name. The present author, unwilling to change his colleague's preference in this case, nevertheless begs to suggest that such a binomial as P. listeri would probably at once make future history of the species less eventful, and honor the memory of England's latest and most distinguished student of the group he loved.
28. Physarum nucleatum Rex.
- 1891. Physarum nucleatum Rex., Proc. Phil. Acad., p. 389.
Sporangia gregarious, spherical, ½ mm., white, stipitate; peridial wall membranaceous, rupturing irregularly, thickly studded with rounded white lime-granules; stipe about 1 mm., subulate, yellowish-white, rugose; columella none, capillitium dense, snow-white, with minute, white, round or rounded nodes, in the centre a conspicuous mass of lime forming a shining ball, not part of the stipe although sometimes produced toward it; spore-mass black; spores brown-violet, delicately spinulose, 6–7 µ.
This species most nearly resembles in appearance and habit of growth P. globuliferum Pers., but may be distinguished from it by the absence of a columella, by the central ball of lime, and the very small rounded lime-granules in the meshes of the capillitium. Exceptionally the lime granules of the sporangium wall are sparse or absent entirely, in which case the wall has a silvery or coppery metallic lustre.
Pennsylvania, Nicaragua.
29. Physarum wingatense nom. nov.
[Plate XVI.], Figs. 3, and 9.
- 1876. Tilmadoche columbina (Berk. & C.) Rost., Mon., App., p. 13 (?).
- 1889. Tilmadoche compacta Wing., Proc. Acad. Nat. Sci., p. 48.
- 1894. Physarum compactum List., Mycetozoa, p. 45.
- 1896. Physarum compactum (Wing.) Morg., Jour. Cin. Soc., p. 91.
- 1899. Tilmadoche compacta Wing., Macbr., N. A. S., p. 61.
- 1916. Physarum columbinum (Rost.) Sturg., Mycologia, Vol. VIII., p. 4.