PHYSARUM.] 
PnYSARACBil?. 
53 
and capillitium with white lime-knots, answering to Berkeley's descrip- 
tion of D.2nmllum (Grev., ii., 1873, p. 53) and to that given above of 
Plujsamm calidris. On the other shp of wood are several specimens 
of a Didijmium with orange stalks, crystalline deposits of lime on the 
sporangiiim-wall, and a large white columella. These resemble the 
type and correspond with Berkeley's description of his D. proximiim 
(Grev., ii., 1873, p. 52), which is the same species as D. xanthnpuR Fr. 
Owing' to the combination of these two specimens, Eostafinski has 
given^JD. pusillum as a synonym for D. jiroximum, only noticing the 
characters of the latter. The first part of Saccardo's description of 
D.jjroximum (Syll, vii., p. 380) is taken from Berkeley's account of 
D. pusillum in Grevillea, I.e., while the second part is a translation of 
Rostafinski's account of D. p)roximum ; hence a confusion has arisen, 
and it would be well if the name D. 2msillum Berk, were dropped, or 
retained only as a synonym for P. calidris. 
Hah. On dead leaves, etc.— Lyme Eegis, 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. Ltis., p. 97 (1805). 
Plasmodium white, on decayed polyporus, dead leaves, etc. Total 
height 1 to 1*5 mm. Sporangia reniform or irregularly ovoid, 
compressed, erect, splitting along the upper ridge ; stipitate, 
sessile, or plasmodiocarps ; 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 
Hme 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 echiijtilate, 9 to 14 /a diam. — 
Sacc, Syll., vii., p. 337. Physarum nephroideum Rost., Mon., p. 93, 
figs. 80-82 ; Mass., Mon., p. 285. Physarum candidum Rost., 
Mon., p. 96 ; Mass., Mon., p. 286. Physarum affine Rost., Mon., 
App., p. 5 J Mass., Mon., p. 283. Physarum PMllipsii Balf. fil., in 
Grev., vol. x. (1882), p. 116; Mass., Mon., p. 290. Didymium 
glaucum Phill., in Grev., vol. v, (1876), p. 114. Physarum 
glaucum Mass., Mon., p. 284. Didymium radiatum Mass., Mon. 
(in part), p. 229. Physarum nicaragitense Macbride, in Bull. 
Nat. Hist. Iowa, vol. u., p. 382. 
The sporangia of P. compressum vary extremely in shape and general 
appearance, and in gome 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. cinereum — the sessile forms are separated by the dark spores ; 
from P. didermoidcs 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 diflFerencc is found in the size and roughness of the spores in 
sporangia from the same cultivation. In some groups they measure 
