136 THE NORTH AMERICAN SLIME-MOULDS 



common snow-white hypothalline base. The distinct habits of the 

 two species are represented in Figs. 5 and 7. In the one the distinct 

 sporangia are associated but not crowded ; in the other all are massed 

 together in quite aethalioid fashion, forming circumambient, chalky 

 masses of considerable size, 2 or 3 cm., overcrowded, superimposed, 

 where the sporangia are regular in shape and size by reason of mutual 

 pressure. The plasmodium develops in forests and orchards, among 

 decaying leaves, but is inclined to rise as maturity draws near, to 

 ascend some twig erect, or the stem of a living plant to the height of 

 several inches where the sporangia at length appear "heaped and 

 pent", an encircling sheath, conspicuous after the fashion of a spu- 

 maria for which it is indeed sometimes mistaken. 



6. DiDERMA LYALLii (Massee) Macbr. 



Plate XVIII., Figs. 5 and 5 a 



1892. Chondrioderma lyallii Massee, Mon., p. 201. 



1894-. Chondrioderma lyallii Mass., List, Mycetozoa, p. 81. 



1899. Diderma lyallii Mass., Macbr., N. A. S., p. 99. 



1911. Diderma lyallii List, sub-species, Mycetozoa, 2nd ed., p. 105. 



Sporangia obovate, more or less closely crowded, white, stipitate, 

 about 1 mm. in diameter, the outer peridium firm, stout, encrusted, 

 especially above, with granular masses of lime, the inner well devel- 

 oped, more or less cartilaginous, opaque, yellow or buflf-colored ; 

 hypothallus well developed, venulose, white, passing up unchanged 

 to form the short, stout stipe and lower outer peridium; columella 

 prominent, half the height of the sporangium, brown ; capillitium of 

 short, brown threads, rigid, much branched, forming a net, widened 

 irregularly and especially at the net-nodes; spore-mass black, spores 

 by transmitted light bright brown, rough, 15-17 fi. 



A very distinct species; large, fine, showy sporangia in more or less 

 crowded clusters spring from a snow-white, common hypothallus. 

 First reported from western Canada. Our first specimens were col- 

 lected by the late Mr. Charles Irish, on the eastern slopes of the 

 Sierras, in Nevada; now coming in abundantly from all the western 

 mountains to the Pacific. 



