PHYSARUM 41 



lime in the capillitium is also notably variable. Specimens 

 occur which in so far realize Rostafmski's Crateriachca ; that is, 

 the lime is massed as a snow-white pseudo-columella in the 

 centre of each sporangium. In such cases the lime of the outer 

 peridium is scant or limited in amount, never forming the cal- 

 careous cap shown in Fig. i. The size of the spores is also 

 variable. Rostafinski gives 12.5-14.2 ; not infrequently a single 

 spore reaches 167-1! 



The species is not common in Iowa, but can be obtained in 

 quantity where once it appears, as the plasmodia are profuse. 



Ohio, Carolinas, Tennessee, Iowa, South Dakota, Kansas. 

 Especially to be looked for on the bark of fallen stems of Popu- 

 lus and Ne;nndo, 



"cb 



19. PHYSARUM NEFROIDEUM Rostafinski. 



PLATE IX., Figs. 2, 2 a, 2 b ; PLATE XV., Fig. 2. 



The history of this species seems to be as follows : 



1805. Physaritm compressum Alb. and Schw., Fung. Lus,, p. 97. (?) 



1809. Physarum griseum Link, Diss., I., p. 27. 



1829. Physarum cernuum (Schum.) (in part), Fries, Syst. Myc., p. 130. 



1873. Didymiitm connatum Peck, Rep N. Y. Mus., XXVI., p. 74. 



1875. Physarum nefroideum Rost., Mon., p. 93. 



1875. Physarum affine Rost, Man., p. 94; App., p. 5 



1875. Physarum lividum Rost., Mon., p. 95. 



1876. Didymium glaucum Phillips, Grev., V., p. 114. 



1879. Physarum polymorphnm (Mont.) Rost., Peck, Rep. N. Y. Mus., 



XXXI., p. 55' 



1882. PJiysarum pJiillipsii Balfour Fil., Grev., X., p. 116. 



1892. Physarum glaucum (Phill.), Massee, Man., p. 284. 



1892. PJiysarum nefroideum Rost., Massee, Man., p. 285. 



1893. Physarum leucophccum Fries, Macbride, Bull. Lab. N~at. Hist. Iowa, 

 II., p. 156. 



1896. Physarum conne.rmn Link., M organ. Jour Gin. Soc., p. 92. 

 1896. PJiysarum conflnens Pers., Morgan, I.e., p. 94. 



Sporangia gregarious, sessile, stipitate, or even plasmodio- 

 carpous ; when stipitate, globose, depressed, or anon reniform, 

 usually concave or umbilicate below, the peridium strongly 

 calcareous, cinereous-white ; stipe variable, generally tapering 

 upward, always distinctly deeply plicate-furrowed, varying in 



