78 THE NORTH AMERICAN SLIME-MOULDS 



treme base where it is lightly attached, a stem which is simply a sack 

 stuffed with yellow lime-granules; — this and the yellow capillitium 

 are distinguishing features. The capillitium and spores suggest Til- 

 madoche viride, but the entire habit precludes such reference. Perhaps 

 nearest to P. melleum. 



Castillo, Nicaragua. 



Miss Lister thinks this the same as P. tenerum Rex. But the whole 

 habit and external appearance are different ; the stipe notably long, 

 clumsy, surcharged with lime; a very singular form. 



36. Physarum didermoides (Pers.) Rost. 



Plate IX., Figs. 1, 1 a, 1 ^, 1 c. 



1801. Spumaria (?) didermoides Acharius, Pers., Syn. Fung., p. xxix. 



1829. Diderma oblongum Fr., Syst. Myc, III., p. 103. 



1831. Spumaria licheniformis Schw., N. A. F., p. 261, No. 2364. 



1832. Physarum atrum Schw., Syn. Fung., Am. Bor., p. 258. 

 1875. Physarum lividum, Schw., Rostafinski, Mon., p. 96. 

 1875. Physarum didermoides (Ach.) Rost., Man., p. 97. 



Plasmodium pale, watery-white or gray; sporangia crowded, ovoid 

 or cylindric, stipitate or sessile, blue-gray, often capped with white; 

 stipe variable in length and structure, where well developed pure 

 white, often flattened, expanded and diaphanous, connate with others 

 through the irregular reticulate or sheet-like hyphothallus ; columella 

 none; capillitium ample, the lime knots angular or rounded, white 

 connected by hyaline threads; spores in mass black, by transmitted 

 light dark violet, decidedly spinulose, 12-15 fi. 



A very variable species in many particulars. The sporangia in the 

 same cluster are stipitate and sessile, ovoid and spherical. Our de- 

 scription does not quite agree with that of Rostafinski. As may be 

 seen from the plate, it is the outer peridium that is with us white, 

 burdened with lime, the inner is simpler and comparatively thin. 

 The whiteness of the outer peridium is however, easily displaced. 

 The colony may not show it at all, in which case the peridia remain- 

 ing give to the fructification entire a pale lead color, very character- 

 istic. The disposition of the lime in the capillitium is also notably 

 variable. Specimens occur which in so far realize Rostafinski's Cra- 

 teriachea; that is, the lime is massed as a snow-white pseudo-columella 



