PHYSARACEM 23 



This order is recognizable by several characteristics, but is espe- 

 cially marked by the peculiar calcareous deposits which affect the 

 capillitium or peridium, now one, now the other, more often both. 



As here defined, the order Physarales includes two distinct fami- 

 lies ; of the one Physarunij of the other Didymium, is type. 



Key to the Families of the Order Physarales 



A. Fructification often calcareous throughout; capillitium intricate 



Physaraceae 



B. Calcareous deposits, when present, affecting the peridium only, or some- 

 times the stipe, in the typical genus plainly crystalline; capillitium simple 



Didymiaceae 



A. PHYSARACEiE 



Key to the Genera of the Physaraceae 



A. Fructification zethalioid 1. Fuligo 



B. Fructification plasmodiocarpous or of distinct sporangia. 



a. Peridium evidently calcareous. 



i. Capillitium calcareous throughout . . 2. Badhamia 

 ii. Capillitium largely hyaline. 



* Sporangia globose, etc.; dehiscence irregular 



3. Physarum 

 ** Sporangia vasiform or more or less tubular 



t Dehiscence by a lid or more or less circumscis- 



sile 4. Craterium 



tt Dehiscence irregular, peridium introverted 



5. Physarella 



b. Peridium apparently limeless, at least outside. 



i. Plasmodiocarpous .... 6. Cienkoivskia 

 ii. Sporangia distinct 7. Leocarpus 



C. Extra-Iimital. 



a. Sporangia stipitate, saucer-shaped, following No. 3 Trichamphora 



b. Sporangia elongate allantoid, etc., following No. 1. Erionema 



1. Fuligo (Haller) Pers. 



1753. Mucor Linn., Sp. PI. II., No. 1656 (?). 



1768. Fuligo Haller, Hist. Helv., Nos. 1233-1235, in part. 



1801. Fuligo Haller, Pers. Syn., p. 159. 



1809. /Et/ialium Link, Diss., I, p. 42. 



1829. JEthalium Fries, Sym. Myc, III., p. 92. 



