340 PROCEEDINGS OF THE AMERICAN ACADEMY. 



colorless, spherical, very small, 2/^-3/^ in diameter. This form has 

 been met with several times on decaying agarics." France. 



Neither of the two preceding forms have been found in American 

 cultures, hence the writer can add nothing to our knowledge concerning 

 them. 



Dictyostelium brevicaule nov. sp. 



Sorus white ; stalks 1-3 mm. high. Spores oval, 3/i,-4ju, X Afi-7[i 

 or rarely spherical and Sfx—i/x in diameter. 



Dung of sheep and goat. Cambridge, Mass. 



A small, erect fructification, quite constant in the possession of a short 

 rather rigid stalk bearing a sorus of comparatively large size and very 

 different in aspect from the long, luxuriant, frequently flexuous, fructifi- 

 cations of D. mucoroides and D. sphcerocephalum. Throughout the four 

 years that this species has been kept growing in laboratory cultures, it 

 has retained its original distinct characters. 



Dictyostelium purpureum nov. sp. 



Sorus and stalk purplish or violet ; when mature, almost black. Spores 

 oval, rarely somewhat inequilateral, 3/x-o/.i X 5/x-8/i,. 



Dung of mouse, toad, cow, horse, sheep, muskrat. Cambridge, Mass.; 

 Indiana ; Florida. 



This distinct species, well-marked by its color, was collected in Aug- 

 ust, 1897, in Crawfordsville, Indiana, on mouse dung cultures, and in 

 October of the same year by Dr. Thaxter in Eustis, Florida, on toad 

 dung. Both forms have been cultivated ever since in the laboratory, 

 with no particular precautions as to the dissemination of the spores, and 

 it is not impossible that the fructifications which appeared at Cambridge 

 on sub-strata other than the two just mentioned represent laboratory 

 escapes. 



Dictyostelium aureum nov. sp. 



Mature sori light to golden yellow, 1.5mm. -4mm. high. Spores oval, 

 or frequently inequilateral, 2.5fi-S/x X 5^-8/a. 



Mouse dung from Porto Rico. 



This species, communicated by Dr. Thaxter, is quite well defined 

 through the color of its fructifications, but especially so by its myxamoebse 

 and its manner of^growth. It matures very slowly on a horse dung de- 

 coction or on other media especially favorable for the rapid development 

 of the common species ; while the myxamoeboe, instead of possessing the 



