DIDYMIACEM 113 



stellately. At centre of the capillitium is a calcareous core. The 

 Plasmodium is yellowish white, spread in rich and beautiful reticula- 

 tions. N.A. F., 1123. 



A plasmodiform gathering of this species which will be mistaken 

 for an entirely diflferent thing, is yellow, sessile, and has adherent 

 spores; looks like a badhamia, but is after all a leocarpus and prob- 

 ably belongs here. The spores are irregularly clustered and the 

 badhamioid section of the capillitium seems now dominant. 



California. 



B. DIDYMIACE/E 



Key to the Genera of the Didymiaceae 



1. Fructification asthaliold - 1. Mucilago 



2. Fructification plasmodiocarpous, or forming more often distinct spo- 



rangia. 



a. Calcareous deposits crystalline, stellate . . 2. Didymium 



b. Calcareous deposits amorphous, peridium double 3. Diderma 



c. Calcareous deposits in form of scattered scales 4. Lepidoderma 



d. Peridium double, the outer gelatinous . . 5. CoUoderma 



1. Mucilago (Mich.) Adans. 



1729. Mucilago Micheli, Nov. PI. Gen., in part. 



1763. Mucilago (Mich.) Adanson, Fam. des PL, II., p. 7. 



1791. Spumaria Pers. in Gmelin, Syst. Nat., II., p. 1466. 



Fructification asthalioid, consisting generally of large cushion- 

 shaped masses covered without by a white foam-like crust; within, 

 composed of numerous tubular sporangia, developed from a common 

 hypothallus, irregularly branched, contorted and more or less con- 

 fluent; the peridial wall thin, delicate, frosted with stellate lime- 

 crystals, which mark in section the boundaries of the several sporan- 

 gia; capillitium of delicate threads, generally only slightly branched, 

 terminating in the sporangial wall, marked with occasional swellings 

 or thickenings. 



By the descriptions offered by most authors, and especially by Ros- 

 tafinski's figures {Mon., PI. ix.), a pronounced columella is called for 

 in the structure of Spumaria. The individual sporangia rise from a 

 common hypothallus, and occasionally portions of this run up and 



