PHYSAEUM.] PHYSARACE^.. 53 



and capillitium with white lime-knots, answering to Berkeley's descrip- 

 tion of D. pusillum (Grev., ii., 1873, p. 53) and to that given above of 

 Physarum calidris. On the other slip of wood are several specimens 

 of a Didymium with orange stalks, crystalline deposits of lime on the 

 sporangium-wall, and a large white columella. These resemble the 

 type and correspond with Berkeley's description of his D. proximum 

 (Grev., ii., 1873, p. 52), which is the same species as D. xanthopm Pr. 

 Owing to the combination of these two specimens, Rostafinski has 

 given D. pusillum as a synonym for D. proximum, only noticing the 

 characters of the latter. The first part of Saccardo's description of 

 jD. proximum (Syll., vii., p. 380) is taken from Berkeley's account of 

 D. pusillum in Grevillea, l.c , while the second part is a translation of 

 Rostafinski's account of D. proximum ; hence a confusion has arisen, 

 and it would be well if the name D. pusillum Berk, were dropped, or 

 retained only as a synonym for P. calidris. ' 



Hah. On dead leaves, etc. — Lyme Regis, Dorset (L:B.M.29) ; 

 Luton, Beds. (L:B.M.29) ; Wothorpe, Northampton (K. 1549) ; Orton, 

 Leicester (K. 1411) ; Linlithgow (K. 1504) ; France (Paris Herb.) ; 

 Parma (B. M. 496) ; Ceylon (B. M. 453) ; S. Carolina (B. M. 858). 



21. P. compressum Alb. & Schw., Fung. Lus., p. 97 (1805). 

 Plasmodium white, on decayed polyporuSjdead leaves, etc. Total 

 height 1 to 1'5 mm. Sporangia reniform or irregularly ovoid, 

 compressed, erect, splitting along the upper ridge ; stipitate, 

 sessile, or plasmodiooarps ; scattered, closely aggregated or con- 

 fluent ; white or grey, rugose or warted ; sporangium- wall mem- 

 branous, colourless, or purplish below, with dense innate clusters 

 of white lime-granules. Stalk stout, equal, furrowed', black from 

 contained refuse matter, or brownish or white from deposits of 

 lime in the wall, never with chalk-white fracture at the base. 

 Columella none. Capillitium a network formed of very numerous 

 white lime-knots, varying in shape and size, connected by rather 

 short, seldom branching, hyaline threads,. Spores dark purplish- 

 brown, more or less spinulose or echiijulate, 9 to 14 /a diam. — 

 Sacc, Syll., vii., p. 337. Physarum nephroideum Host., Mon., p. 93, 

 figs. 80-82 ; Mass., Mon., p. 285. Physarwm candidum Eost., 

 Mon., p. 96 ; Mass., Mon., p. 286. Physarum ajfftne Eost., Mon., 

 App., p. 5 ; Mass., Men., p. 283. Physarum, PhilMpsii Balf. fil., in 

 Grev., vol. x. (1882), p. 116; Mass., Mon., p. 290. Didymium 

 glauMom Phill., in Grev., vol. v. (1876), p. 114. Physarum 

 glaucum Mass., Mon., p. 284. Didymium radiatum Mass., Mon. 

 (in part), p. 229. Physarwm nicaraguense Macbride, in Bull. 

 Nat. Hist. Iowa, vol. ii., p. 382. 



The sporangia of P. compressum vary extremely in shape and general 

 appearance, and in some forms resemble those of the following allied 

 species, from which they may be distinguished by the characters as 

 under : — From P. nutans by the abundant lime-knots and dark spores ; 

 from P. einereum — the sessile forms are separated by the dark spores ; 

 from P. didermoides by the presence of refuse matter in the stalk and 

 by the single sporangium-wall ; from P. bivalve by the darker spores 

 and shorter plasmodiocarps. 



Much difference is found in the size and roughness of the spores in 

 sporangia from the same cultivation. In some groups they measure 



