114 THE NORTH AMERICAN SLIME-MOULDS 



give to a sporangium the appearance of being stipitate. Sometimes 

 also this upper extension of the hypothalline protoplasm passes be- 

 yond or behind the base of the sporangium or between two or more, 

 and is more or less embraced by these in their confluent flexures. 

 This, it seems, suggested Rostafinski's elaborate diagram, Fig. 158; 

 at least, none other form of columella is shown by American mate- 

 rials at hand. 



1. MuciLAGO SPONGIOSA (Leyss.) Morgan. 



1783. Mucor spongiosus Leysser, Fl. Hal, p. 305. 



1791. Reticularia alba Bull., C. FL France, p. 92. 



1791. Spumaria mucilago Pers., Gmel., Syst. Nat., II., 1466. 



1805. Spumaria alba (Bull.) DC, FL Fr., II., p. 261. 



1897. Mucilago spongiosa (Leyss.) Morg., Bot. Gaz., XXIV., p. 56. 



-^thalium white or cream-colored, of variable size and shape, half- 

 an-inch to three inches in length and half as thick, the component 

 sporangia resting upon a common hypothallus and protected by a 

 more or less deciduous calcareous porous cortex ; peridial walls thin, 

 and where exposed iridescent, generally whitened by a thin coating of 

 lime crystals; capillitium scanty, of simple, mostly dark-colored, 

 slightly anastomosing thieads; columella indefinite or none; hypo- 

 thallus white, spongy; spore-mass black, spores violaceous, exceedingly 

 rough, large, 12-15 fi. 



Very comhnon in all the eastern United States and the Mississippi 

 valley, south to Texas. The Plasmodium is dull white, of the con- 

 sistence of cream, and is often met with in quantity on beds of decay- 

 ing leaves in the woods. In fruiting the Plasmodium ascends prefer- 

 ably living stems of small bushes, herbaceous plants, or grasses, and 

 forms the aethalium around the stem some distance above the ground. 

 The cortex varies in amount, is also deciduous, so that weathered or 

 imperfectly developed forms probably represent the var. S. cornuta 

 Schum. 



Two varieties of this species are recognized ; the one from Bolivia, 

 var. dictyospora described by Mr. R. E. Fries {Arkiv. for Botanik 

 Bd. 1, p. 66) differs from the type chiefly in its finer capillitial 

 threads its darker spores with longer spines and fine reticulate sculp- 

 ture; the other from Colorado, var. solida described by Professor 



