294 A Monograj^h of the Muxoaastres. 



A very distinct species, sporangia I'o — 2 mm. high, scattered 

 singly or in groups of two or three. Most nearly related to 

 Physarum rnhiginosum, Fr., but readily distinguished by the 

 smaller spores, and the scattered stipitate sporangia. Readily 

 distinguished from the red form of Physarum ScJmmachcri, by 

 the absence of a columella and the pyriform sporangium passing 

 insensibly into the short stem. 



Physarum atrorubrum, Peck. 



Scattered or gregarious, stipitate ; sporangia globose, even or 

 somewhat wrinkled, dark-red ; stem cylindrical, even, blackish 

 or subconcolorous, capillitium when cleared of the spores 

 whitish, sometimes with a slight pinkish tinge ; columella none ; 

 spores globose, smooth, dark-brown in the mass, dark-red when 

 separated, -0008— -00035' in diameter ( = about 8—9 /x). 



Physarum atrorulrum; Peck, 31st Report, N. York State 

 Mus., p. 40; Sacc, Syll., vii., 1, n. 1202 (as Physarum atro- 

 piirpurciim by mistake). 



Decaying wood. Adirondack Mts., U. States. 



The plants are scarcely one line high. The capillitium is 

 very delicate, and when cleared of the spores the knot-like 

 thickenings are seen to be very small and of a dark-red colour, 

 to which probably is due the pinkish tinge sometimes observed. 

 The dark-red granules of the sporangium walls are abundant, 

 and appear to form a coatinuous crust. (Peck.) 



Physarum roseum, B. and Br. 



Sporangia stipitate, globose, broadly elliptical or obovate, 

 dark reddish-jnnjile, sporangial wall covered with a thin crust 

 of minute granules of lime; stem brownish-purple, equal, 

 longitudinally wrinkled, filled with granules of lime, equal to 

 or usually lunger than sporangium, expanding at the base into 

 a small, circular, pale brown, wrinkled h}^othallus ; capil- 

 litium well developed, threads thin, tinged pink, tvith sndtered, 

 eUijitical, interstitial swcllinys containing lime, nodes not usually 

 enlarged or containing granules ; spores globose, smooth, 10 — 11 m 

 diameter. 



