60 ENDOSPORE/E. [PHYSARUM. 



Plate XXI., A. a. sporangia, var. a, x 20 ; b. capillitium, with fragment 

 of sporangium- wall showing calcareous discs, and spores, x 280 ; c. spore, 

 x GOO (England). 



B. a. sporangia, var. j3, x 20; b. capillitium and spores, x 280 (England). 



Glycerine mountings of a. genulmim show, dispersed in the sporangium- 

 wall, flattened disc-shaped crystalline bodies with a radiating structure, 

 measuring 10 to 20 p diameter, such as are also found in the sporangium- 

 wall of P. psittacinum and Oraterium leucocephalum. They do not 

 appear to be present in vars. /3 and y of P. virescens. Didymium 

 trrrigenuin Berk. & Curt., from Carolina (B. M. 575), is given by Host. 

 as a synonym for Pliysarum cmereum Host., Mon., App., p. 9. The 

 specimen is in a poor condition, but the character of the sporangia 

 and spores and the orange-yellow lime-knots places it under P. riresccns. 

 The specimen from Iowa (B. M. 1011), to which Prof. Macbride applied 

 the name P. aurisealpium Cooke (/.c.), is P. rirescens y nitens. 



Hab. On dead leaves, grass, etc. a. Epping Forest, Essex (L:B.M. 

 37). j3. Lyme Regis, Dorset (L:B.M.37) ; a. France (Paris Herb.) ; 

 a. Germany (B. M. 413) ; /3. Hungary (K. 1529) ; a. Dorfhalden (B.M. 

 861). y. Maine (L:B.M.37) ; a. Massachusetts (L:B.M.37) ; y. Iowa 

 (B. M. 1011). 



29. P. inaequale Peck, in Rep. N. York Mus. Nat. Hist., xxxi., 

 Bot., p. 40 (1879). PlasHiodiurn ? Sporangia subglobose, 0'3 to 

 0'7 mm. diam., sessile, or elongated and confluent forming plas- 

 modiocarps, gregarious, yellowish-red, brick-red, rosy-red, or when 

 little lime is present pale bluish spotted with red, somewhat 

 rugose, rupturing irregularly ; sporangium -wall membranous, 

 colourless above, yellow at the base, with innate clusters of red or 

 yellow lime-grannies. Columella none. Capillitium a network 

 of delicate hyaline colourless or pale yellow threads, with rounded 

 lime-knots varying in shape and size, each knot with a red centre 

 surrounded by yellow round lirne-grannles 1 to 3 /x diam. Spores 

 pale violet-brown, almost smooth, 6 to 9 //, diam. Didymium 

 lateritium Berk. & Eav., in Grev., ii. (1873), p. 65. Physarum 

 Ditmari y lateritium Eosfc., Mon., App., p. 9. Didymium croceo- 



flavum Berk. & Br., in Linn. Journ., xiv. (1875), p. 84. Phy- 

 sarum Ditmari (3 croceoflavum Host., Mon., App., p. 9. Physarum 

 chrysotrichum Mass., Mon., p. 300 (in part). 



Plate XXII. , B. a. sporangia, x 20 ; b. capillitium with fragment of 

 sporangium-wall and spores, x 280 ; c. spore, x GOO (S. Carolina : 

 Berkeley's type of D. lateritium'). 



Intermediate between P. rubiginosum and P. rirescens ; from orange 

 forms of the latter it differs in the scattered habit of its sporangia, 

 and from both species in the curious structure of the rounded lime- 

 knots. 



Hab. On dead leaves, wood, etc. Ceylon (B. M. 414) ; Georgia, 

 U.S.A. (B. M. 898) ; S. Carolina (B. M. 898, 899) ; Philadelphia 

 (L:B.M.38) ; Ohio (L-.B.M.38). 



30. P. rubiginosum Fries, Symb. Gast., p. 21 (1817). Plas- 

 modium 1 Sporangia subglobose, 0'5 to 0'8 mm. diam., sessile, 

 gregarious or crowded, smooth or rather rough, orange or deep 



