I 50 THE NORTH AMERICAN SLIME-MOULDS 



hypothallus at first conspicuous as a white margin extending 

 round the entire asthalium, evanescent without, but persisting 

 as a firm membrame beneath the spore-mass; pseudo-capillitium 

 abundant, tending to form erect central masses which persist 

 long after the greater part of the fruit has been scattered by 

 the winds ; spore-mass umber, spores by transmitted light pale, 

 reticulate over about two-thirds of the surface, the remainder 

 slightly warted, 8-9 //.. 



Not common. Often confused with the following, the spores 

 of the two forms being very much alike ; the internal structure 

 is, however, entirely different, and once compared, the two are 

 thereafter easily distinguished at sight by external characters. 

 The internal structure is indifferent. It represents a phase in 

 development whence might issue either columellae with capilli- 

 tium branches or distinct tubular sporangia with persisting walls. 

 Compare Amauroch&te atra, where similar conditions prevail. 

 There differentiation goes on to the formation of a structure of 

 which Stemonitis is type ; here the sporangium wall becomes 

 dominant ; suffers modification for spore disposal, of which the 

 climax appears in Cribraria and Dictydium. We cannot regard 

 the aethalium in this case as reversionary. 



Widely distributed. Maine to California, and south. 



2. Enteridium Ehrcnbcrg. 

 1818. Enteridium Ehrenberg, Link and Sprang., Jahrb., Bd. II., p. 55. 



Fructification aethalioid ; the confluent sporangia inextricably 

 interwoven, the walls perforate by large openings, the resultant 

 network of broad plates and bands widening at the points of 

 intersection. 



The genus Enteridium is distinguished from Rcticularia 

 chiefly by the more perfectly developed sporangial walls. 

 These are everywhere membranous and do not show the 

 abundant filiform dissipation so characteristic of Rcticularia. 

 The resultant structure in Reticularia is a mass of more or less 

 lengthened and anastomosing threads ; in Enteridium, an ex- 



