1893. _Physarum nicaraguense_ Macbr., _Bull. Lab. Nat. Hist. Iowa_, II., p. 383. 1894. _Physarum compressum_ Alb. & Schw., List., _Mycetozoa_, p. 53, in part. 1910. _Physarum nicaraguense_ Macbr., Petch, _Mycetozoa Ceylon_, p. 334. 1911. _Physarum reniforme_ List., _Mycetozoa, 2nd ed._, p. 72, in part. Sporangia multilobate or compound-contorted, below obconic, gray, ribbed with calcareous thickenings; stem short, fuscous, longitudinally wrinkled; hypothallus distinct, black; columella none, although the lime massed at the centre of each sporangium simulates one; capillitium white, densely calcareous, with heavy angular nodules connected with comparatively short threads; spores violet, globose, spinulose, about 12 mu in diameter. Ometepe, Nicaragua. _Professor B. Shimek_. This species resembles in some particulars No. 39, especially in the amount of lime present in both capillitium and peridium, in the fluted, sooty stipe, and the rough spores. Mr. Lister once regarded it as the same. Nevertheless, it differs from _P. notabile_ in many definite particulars. In the first place, the sporangia are different in form and habit. They are obconic, nearly always compound, convolute, or botryoid, in this respect somewhat resembling _P. polycephalum_. Besides, the sporangia are uniformly much smaller, and show constantly the strongly calcified centre, much transcending anything seen in _P. notabile_. The stipe also is peculiar, quite short, an upward extension or sweep of the common hypothallus which is usually very distinct or prominent; and, while the stipe is longitudinally wrinkled, it is much less so than in the related species, and in a different way. The spores are about the same in size, but differ in color, in this respect agreeing rather with _P. leucophaeum_. In the _Mycetozoa, 2nd ed., l. c._, the present species is entered as a synonym of two described by Massee: _Tilmadoche reniformis_ Mass., Mon., p. 336, and _Didymium echinosporum_ Mass., _Mon._ 239. But Massee's description of his tilmadoche is, naturally enough, at variance in every important point with the facts in the species before us. Massee says: "... sporangia deeply umbilicate _below_, sausage-shaped and curved; the stem elongated slender erect, pale brown; capillitial nodes scattered, fusiform, colorless or yellow; spores 16-17 mu." It is evident that whatever Massee may have had in hand as he wrote it was _not P. nicaraguense_, which has spores 10-12 mu and reverses the remaining description.