138 THE NORTH AMERICAN SLIME-MOULDS 



litium abundant, made of threads of two sorts, some purplish or 

 dusky, with pale extremities, uneven, others more delicate and color- 

 less, and with wart-like thickenings, all sparingly branched; spores 

 violet-brown, minutely roughened, 9-10 /x. 



This species is not common. From Colorado we have fine speci- 

 mens typical in every way. Specimens from Washington are flat so 

 far as at present at hand; probably represent D. deplanatum (R.) 

 List., which the last named author regards as varietal of the present 

 species, entering it and Z>. lyallii as sub-species 2 and 1 respectively. 

 D. deplanatum may perhaps be best so disposed of; but D. lyallii is 

 distinguished at sight, as well as by microscopic characters, spores 

 nearly twice as great, rougher and different in color. 



9. DiDERMA CINEREUM Morg. 



1894. Diderma cinereum Morg., Myx. Mi. Val., p. 70. 



Sporangia gregarious, more or less crowded or even confluent, sub- 

 globose, only slightly depressed, ashen white; the peridium not ob- 

 viously double, very smooth and thin, rupturing irregularly; hypo- 

 thallus an indistinct membrane or wholly wanting; columella large, 

 globose or hemispheric, white, the surface granulose; capillitium of 

 very slender colored threads, the extremities pellucid, more or less 

 branched ; spores violaceous, minutely warted, 9-1 1 fx. 



Growing on old wood, leaves, etc. The sporangium .3-.5 mm., 

 thin and smooth or rugulose. This elegant little species I know only 

 from specimens received from Mr. Morgan. It seems to be closely 

 related to D. spumarioides, from which it is distinguished by its color, 

 darker, and its smoother, or less spinulose spores. The author com- 

 pares the color and external appearance to that of P. cinereum, — 

 Jour. Cln. Soc, XVI., p. 154. 



Ohio, Pennsylvania. 



10. Diderma hemisphericum (Bull.) Home. 



1791. Reticularia hemisp/ierica Bull., Cham, de Ft., I., p. 93. 



1829. Didymium hemisphericum (Bull.) Fr., Syst. Myc, III., p. 115. 



1829. Diderma hemisphericum (Bull.) Home., Fl. Dan., XL, p. 18. 



1832. Didymium michelii Lib., PI. Ard., No. 180. 



1873. Chondrioderma michelii (Lib.) Rost., Fuckel, Sym. Myc, p. 74. 



