132 THE NORTH AMERICAN SLIME-MOULDS 



in such case the compared colony will show somewhere a very short 

 and stout but very real stipe supporting the discoid fruit. 



Rostafinski divided the genus CJiondriodernw, i. e. Diderma, into 

 three sections : — 



Monoderma to include those species in which the calcareous crust is 

 less distinct or connate with the true peridium. 



Diderma, in w^hich the two structures were plainly separate. 



Leangium, used as in the present work. In his first section Rosta- 

 finski placed C. reticulatum and C. michelii; in the second, C. dif- 

 forme and C. calcareurn. 



Lister has examined Rostafinski's type of C. reticulatum and de- 

 clares that it has the usual didermic characters. Hence there is no 

 doubt that our small-spored American specimens are covered by Rosta- 

 finski's description, No. 72. On the other hand. Lister makes C. 

 difforme (Pers.) Rost. a Didymium, by its crystalline coat. That 

 species therefore is removed from consideration in this connection. 

 C. calcareum remains as applicable to American forms having the 

 spores 10-12 ju,, but according to the author of the species the capil- 

 litium is abundant and definitive. Unhappily the type of C. cal- 

 careum is lost (Lister, Mon., p. 95), so that there is no other means 

 of verification than the description and Rostafinski's figure. Under 

 these circumstances we consider the name calcareum inapplicable to 

 any American forms we have so far seen. See next species. As to the 

 American species which have been distributed as C. calcaretim (Lk.) 

 Rost., they are, so far as seen, referable to D. reticulatum (Rost.), 

 Morg. Here also belongs No. 1217, Ellis, N. A. F. 



New York, Pennsylvania, Ohio, Iowa, Nebraska. Probably to be 

 found throughout the eastern United States. 



2. Diderma spumarioides Fries. 



1829. Diderma spumarioides Fries, Syst. Myc, III., p. 104. 

 1833. Physarum stromateum Link., Handb., III., p. 409. 

 1876. Chondrioderma stromateum (Lk.) Rost., A pp., p. 18. 



Sporangia sessile, crowded, spherical, or by mutual pressure ir- 

 regular, white; the peridium plainly double, but the layers adhering, 

 the outer more strongly calcareous, but very frail, almost farinaceous ; 



