The genus _Enteridium_ is distinguished from _Reticularia_ chiefly by the more perfectly developed sporangial walls. These are everywhere membranous and do not show the abundant filiform dissipation so characteristic of _Reticularia_. The resultant structure in _Reticularia_ is a mass of more or less lengthened and anastomosing threads; in _Enteridium_, an exceedingly delicate but sufficiently persistent sponge. The "net-like, three-winged skeleton" referred to by Rostafinski results from the union at one point of three adjoining sporangia. Compare the section of the adjoining cells of a honeycomb. Of this genus there are but two or three species, all so far occurring in our territory. =Key to the Species of Enteridium= _A._ Fructification umber brown 1. _E. splendens_ _B._ Fructification olivaceous 2. _E. olivaceum_ _C._ Fructification minute, 1-2 mm. 3. _E. minutum_ 1. ENTERIDIUM SPLENDENS _Morg._ PLATE I., Figs. 1, 1 _a_, 1 _b_; PLATE XII., Figs. 4, 5. 1876. _Reticularia_ (?) _rozeanum_ Rost., _Mon. App._, p. 33. 1889. _Enteridium rozeanum_ (Rost.) Wing., _Proc. Phil. Acad._, p. 156. 1892. _Enteridium rozeanum_ Wingate, Macbr., _Bull. Lab. Nat. Hist. Iowa_, II., p. 117. 1893. _Reticularia splendens_ Morg., _Jour. Cin. Soc._, p. 11. 1899. _Enteridium splendens_ Morg., Morg. _in litt._ Aethalium pulvinate, even, or somewhat irregular, unevenly swollen or inflated, lobate or compound, covered by an exceedingly thin, generally smooth, shining, but never white, pellicle or cortex, brown, from 1-6 cm. in diameter; hypothallus white, often wide extending; capillitium none; the sporangial walls thin and brown forming a network as above described; spore-mass umber, spores by transmitted light pale, about two-thirds of the surface reticulate, the rest nearly smooth, 7-9 mu. Very common, especially west, on decaying logs and stumps of every description. Easily distinguished by its brown color and smooth, shining, though uneven surface. The plasmodium as it emerges to form fruit is pale pink or flesh color, slowly deepening to brown as maturity advances. The first emergence is a watery white. New England, Canada, to Minnesota and Nebraska, South Dakota.