DIDYMWM 123 



10. DiDYMiUM NIGRIPES (Link) Fries. 



Plate VII., Figs. 2, 2 a, 2 b. 



1809. Physarum nigripes Link, Obs. Diss., I., p. 27. 



1818. Physarum microcarpon Fr., Sym. Gast., p. 23. 



1829. Didymium nigripes (Link) Fr., 5yjA Myc, IIL, p. 119. 



1875. Didymium microcarpon (Fr.) Rost., Mon., p. 157. 



1896. Didymium microcarpon Fr., Morg., 7our. Ci«. Sof., p. 61. 



Sporangia gregarious, globose or hemispheric, umbilicate beneath, 

 small, white, stipitate; the peridium smoky, covered with minute cal- 

 careous crystals; stipe slender, erect, black, opaque; hypothallus scu- 

 tate, black; columella distinct, globose, black or dark brown; 

 capillitium of delicate threads, pale brown or colorless, with occa- 

 sional brown thickenings or nodes, sparingly branched ; spores pale,, 

 violaceous by transmitted light, minutely warted, 6-8 fi. 



This is D. microcarpon Rost. Fries, /. c, acknowledges the prior- 

 ity of Link's appellation, and discards microcarpon. Rostafinski 

 adopted microcarpon simply because he thought it more appropriate. 

 Fries describes the columella "none or black." It is doubtful wheth- 

 er we have the typical Friesian form on this continent. The fructi- 

 fication is in our specimens small, about .4 mm., and the spores, as 

 noted by Morgan, small; otherwise the species is hardly more than a 

 variety of the next. Under the name D. nigripes Lister groups our 

 Nos. 10, 11, 12. N. A. F., 1393, represents Dr. Rex's conception of 

 the present species. 



Not common. New York, Ohio, Iowa. 



11. Didymium xanthopus (Ditmar) Fr. 



Plate XVI., Fig. 10. 



1817. Cionium xanthopus Ditmar, Sturm, Deutsch. Fl., III., p. 37, t. 43. 

 1829. Didymium xanthopus (Dit.) Fr., Syst. Myc, IIL, p. 120. 

 1873. Didymium proximum Berk. & C, Grev., II., p. 52. 

 1892. Didymium microcarpon (Fr.) Rost., Macbr., Bull. Lab. Nat. Hist. 

 Joiva, XL, p. 146, in part. 



1894. Didymium nigripes Fr., List., Mycetozoa, p. 98, in part. 



Sporangia gregarious, white, globose, slightly umbilicate, stipitate; 

 the peridium thin, and nearly or quite colorless, frosted with crystals 

 of lime ; the stipe yellowish or yellowish brown, corneous, erect, sub- 



