62 ENDOSPOREAE [PHYSARUM 



unreif." It has now been obtained from east and west North America, 

 from England, Scotland, and Ireland, from Sweden, Germany, and 

 Portugal, and from Java. 



Hob. On dead wood and moss. — Luton, Beds (B.M. 2149) ; Ireland 

 (B.M. 2150); Upsala (B.M. 2151) ; Lisbon (B.M. 2152) ; Philadelphia 

 (B.M. 1229). 



27. P. citrinellum Peck in Rep. N. Y. Mus. Nat. Hist., 

 xxxi. 55 (1879). Plasmodium ? Sporangia subglobose, 0-6 

 to 0-8 mm. diam., stalked, erect, gregarious, rugose, lemon- 

 yellow or ocliraceous, tinged with orange at the base ; 

 sporangium-wall of two layers, the outer cartilaginous, yellow, 

 rugose, with dense included deposits of lime, easily 

 separating from the colourless membranous inner layer. 

 Columella none. Stalk cylindrical, 0-3 to 0-4 mm. high, stout, 

 plicate, orange-red, translucent. Capillitium a network of 

 colourless hyaline threads, with many large, irregular, and 

 branching white lime-knots. Spores purple-brown, rather 

 strongly spinulose, 10 to 12 /x diam. — Mass. Mon., 278 ; 

 Sturgis in Trans. Conn. Acad., x. 470-472. P. caespitosum 

 Schwein. in Trans. Amer. Phil. Soc, n.s. iv. 258 (1832) ? ; Macbr. 

 N. Am. Slime-Moulds, 37. Didymium flavidum Peck I.e., 

 xxviii. 54 (1879). Diderma citrinum Peck non Fries I.e., xxii. 

 89 (1869). Craterium citrinellum Lister Mycetozoa, 74 (1894). 



PI. 68. a. sporangia (Japan) ; b. sessile sporangia (New Hampshire) ; c. capilli- 

 tium and spores, with fragment of sporangium-wall ; d. spore. 



In the first edition of the present work this species was placed in the 

 genus Craterium in view of its affinity with C. aareum ; as however 

 there is no tendency in P. citrinellum to form on dehiscing a regular cup, 

 it seems better to replace it in the genus Physarum. The slight tendency 

 in C. aureum to form such a cup allows us to regard it as a Craterium, 

 though at this point the distinction between the two genera becomes 

 obviously artificial. Other differences from C. aureum are the more 

 globose stouter-walled sporangia, and the larger rougher spores. 

 Professor Macbride has regarded P. caespitosum Schwein. as being 

 probably the present species, but Schweinitz's type appears to have been 

 lost ; the original description is short and no mention is made of the 

 colour or structure of the stalk ; this reference therefore is very uncertain. 

 Dr. Sturgis has examined the type of P. flavidum, which was first 

 described by Peck under Didymium in 1875, and finds that it is an 

 immature specimen of the present species with sessile or shortly stalked 

 sporangia (see Sturgis, I.e.) ; this name was not actually published, 

 however, till 1879, the year in which a more definitely stalked form of 

 the same species was published by Peck as P. citrinellum, under which 

 name it has generally been distributed in the United States. In the 

 first edition of " Mycetozoa," p. 62, the opinion was expressed that 

 P. flavum Fr. was probably the present species ; but the description 

 given by Fries of the yellowish-white stalks of his P. flavum applies 

 rather to P. sulphureum Alb. & Schw. (q.v. 46) than to P. citrinellum, 

 the stalks of which are orange-red and translucent. P. citrinellum 

 has hitherto been recorded only from the United States and Japan. 



Hab. On dead wood and moss. — Adirondack Mts., N.Y. (B.M. 

 1283, 1892) ; Japan (B.M. 2153). 



