diderma] physaraceae 109 



Carm." is the same form and probably part of the same gathering as 

 K. 403, named " Diderma melaleucum Carm.," with a descriptive note 

 stating that it was gathered in Scotland by Captain Carmichael ; it 

 differs from the Salzburg and American gatherings in the rather darker 

 and larger sporangia, and in the broader, almost simple threads of the 

 more scanty capillitium, but it appears to be the present species. 



Hob. On dead wood and moss. — Appin, Scotland (K. 403) ; Salz- 

 burg, Tyrol (Strassb. Herb.); Portugal (B.M. 2416); Adirondack 

 Mountains, New York (B.M. slide). 



10. D. ochraceum G. C. Hoffin. Deutsch. Fl. Crypt., t. 9, fig. 

 2b (1795). Plasmodium lemon-yellow. Sporangia solitary 

 or in small clusters, sessile, hemispherical, 0*7 to 1 mm. diam., 

 often forming curved and sometimes ring-shaped plas- 

 modiocarps, ochraceous ; outer sporangium- wall somewhat 

 cartilaginous, with abundant deposits of angular or round 

 yellow lime-granules, adhering to or free from the firm mem- 

 branous yellow inner wall. Columella indefinite. Capilli- 

 tium consisting of abundant simple or branching purple- 

 brown threads, often hyaline at the base. Spores purplish- 

 grey, minutely spinulose, 9 to 11 fx. — Chondrioderma ochraceum 

 Schroet. in Cohn Krypt.Fl. Schles., hi. pt. 1, 124 (1885) ; Mass. 

 Mon., 216 ; Lister Mycetozoa, 89, & in Journ. Bot., xxxix. 

 88, tab. 419, figs. 3a, and xliii. 150 ; Torrend Fl. Myx., 166. 



PI. 96. — a. sporangia (X. Wales) ; 6. spores and capillitium showing attachment 

 of threads to sporangium-wall. ; c. spore. 



It appears probable that Hoffmann's type of the present species is 

 represented by an unripe gathering marked " Diderma ochraceum " 

 in Persoon's collection in the Leyden Herbarium. Fries writes that he 

 had examined the type, but could not make out if the capillitium and 

 columella were present or absent (Syst. Myc, iii. Ill) ; he refers it 

 doubtfully to D. granulatum (Schum. ) Fr. Pvostafinski gives both these 

 names as synonyms for Physarum conglomeratum (Ft.) Rost., but 

 Hoffmann's figure of the scattered sporangia, and his description of their 

 being often traversed by the moss leaves on which they occur, are 

 entirely characteristic of the present species. The appropriate specific 

 name ochraceum appears to have been adopted independently by 

 Schroeter for his Silesian gathering. D. ochraceum has repeatedly been 

 found in company with Lepidoderma tigrinum (see Lister Mycetozoa, 

 106), a species which it strongly resembles in capillitium and spores. 

 Specimens of L. tigrinum have been found with the characteristic 

 calcareous discs of the sporangium-wall in part replaced by angular 

 lime-granules similar to those met with in D. ochraceum, and possibly 

 we may have here varying forms of the same species. Repeated observa- 

 tions, however, made in a wooded ravine in North Wales, where both 

 forms were developing daily for about a week, failed to show any 

 connecting links ; the Lepidoderma had always a dark orange stalk 

 and spongy hypothallus while the Diderma had, as constantly, sessile 

 sporangia and no hypothallus ; the former also matured from orange 

 and the latter from lemon-yellow plasmodium. Until we have further 

 light, the two forms must be placed as distinct though nearly allied 

 species. 



