40 ENDOSPORE^. [PIIYSAKUM. 



which are 10 to 50 /t broad and Qlled with globular lime-granules 

 1 to 1-5 u diam. Spores violet-brown, minutely spinulose, 7 to 10 

 u diam.-Eo8t., Men, p. 101 ; Cooke, Myx. Brit p. 12 ; Mass., 

 Mon., p. 287 (in part) ; Macbride, in Bull. Nat. Hist. Iowa, u.,, 

 p. 156. Bidymivm leucopus Fr., Syst. Myc, iii., p. 121. 



Plate VI., A.— a. sporangia, x 20 ; I. capillitinm with fragment of spo 

 rangium-wall and spores, x 280 ; c. spore, x 600 (Bngland). 



The snow-white nearly smooth stalk, which is chalk- white in section 

 to the base, always distinguishes P. leucopus from P. nutans. The 

 lax capillitium, with large lime-knots and the large lime-granules 

 in the knots and sporangium-wall, separate it from P. globuKferum, 

 which is its nearest ally. The types quoted by Rostafinski from 

 Germany and Russia of this well-marked species are not represented 

 in the Strassburg or British collections ; the stations here given are 

 therefore confined to those of the English and American gatherings. 

 It is not common ; the only specimen in the Kew collection (K. 518), 

 leg. J. Henderson, is named Didymium squamulosum. 



Hah. On dead leaves, moss, etc. — Batheaston, Somerset (B.M. 48) ; 

 Lyme Regis, Dorset (L:B.M.ll) ; Ohio (L:B.M.ll) ; New Granada 

 (Paris Herb.). 



2. P. globuliferum Pars., Syn., p. 175 (1801). Plasmodium? 

 Total height 1 to 1-5 mm. Sporangia globose, stipitate, erect, 

 white, gregarious, 0-5 mm. diam. ; sporangium- wall membranous, 

 with crowded clusters of innate lime-granules. Stalk white or 

 pale buflf, sometimes red-brown towards the base, 0-5 to 1 mm. 

 long, -05 to '01 mm.' thick, nearly smooth, brittle, chalky in section. 

 Columella conical. Capillitium persistent, retaining the form of 

 the sporangium after the dispersion of the spores, forming a close 

 network of obtusely branching hyaline threads with numerous 

 fusiform or rounded, white, or pale ochraceous lime-knots 10 to 

 20 /* diam. ; the lime-knots are not usually developed at the 

 axils of the branches, which are flat and triangular, or if 

 present, usually minute. Spores violet-brown, almost smooth, 

 6 to 8 /i diam. Eost., Mon., p. 98, fig. 86,; Mass., Mon., p. 297. 

 Sphcerocarpus globuUferus Bull., Champ., p. 134, PI. 484, fig. 3 

 (1791). Physarum Petersii Berk. & Curt., var. a. Farlowii Eost., 

 Mon., App., p. 6. Physarum albicans Peck, in Eep. New York 

 Mus., XXX., p. 50; Mass., Mon., p. 312. Bidymmm Barteri 

 Mass., Mon., p. 231. Physairwm columbinum Macbride, in Bull. 

 Nat. Hist. Iowa, ii., p. 384. 



Plate VI., B.— a. sporangia, x 20, in two the sporangium- wall has fallen 

 away, leaving the persistent head of capillitium ; J. stalks showing the 

 columella after the capillitium has broken away, x 20 ; c. capillitium, 

 columella, and spojes, x 280 ; d. spore, x 600 (United States). 



The types of P. Petersii var. a Farlowii Rost., and P. albicans Peck 

 are the same species as the type of P. globuliferum in the Strassburg 

 collection. P. columbinum Macbride, from Iowa (B.M. 1012) is also 

 P. globuliferum ; it has snow-white, occasionally red-brown stalks 

 and well-developed conical columellse. Didymium Barteri Mass. (K. 74) 

 appears to have been rightly named by Rostafinski " P. globuliferum 

 immaturum " ; the specimen is obscured by mould. In the specimen 



