20 BRITISH MYCETOZOA. [Physarum. 



io. P. Crateriachea Lister. — Sporangia white, rugose; either 

 ovoid, erect, seated on an ochraceous hypothallus which is often 

 produced into a short stalk, or forming plasmodiocarps. Capillitium 

 a rigid network of hyaline threads ; lime-knots confluent in the 

 centre of the sporangium, and forming an elongate clavate pseudo- 

 columella, sparsely distributed elsewhere. Spores purple-brown, 

 spinulose, 8 /x diam. 



Hab. On rotting herbaceous stems. Rare. 



ir. P. cinereum Pers. — Sporangia sessile, subglobose, or plas- 

 modiocarps, scattered or crowded, 0^3 to 0-5 mm. diam., pale-grey. 

 Capillitium with numerous white lime-knots. Spores violet-brown, 

 nearly smooth, 7 to 10 /x diam. 



Hab. On dead leaves, etc. 



1 2. P. bivalve Pers. — Sporangia sessile, elongate, laterally com- 

 pressed, frill-like, splitting longitudinally, white or buff. Capillitium 

 of numerous white lime-knots connected by short hyaline threads. 

 Spores violet-brown, spinulose, 8 to 10 yu. diam. 



Hab. On dead leaves, etc. 



13. P. Diderma Rost. — Sporangia sessile, subglobose, or elon- 

 gate, sometimes compressed, plasmodiocarps, cr6 mm. or more 

 wide ; the white outer sporangium-wall peeling off and disclosing 

 the purplish inner layer. Capillitium with numerous white lime- 

 knots. Spores purplish-brown, spinulose, 10 to 12 /x diam. 



Hab. On dead leaves, etc. 



14. P. COlltextum Pers. — Sporangia sessile, obovoid, or reniform, 

 curved, crowded, 0-5 mm. diam., ochraceous, the wall densely 

 calcareous. Capillitium of numerous branching white lime-knots 

 with short connecting threads. Spores dark violet-brown, spinulose, 

 10 to 13 jx diam. 



Hab. On dead leaves, etc. 



15. P. conglomeratum Rost. — This species resembles P. con- 

 textutn in general appearance, but differs in the spores, which are 

 pale violet-brown, nearly smooth, 8 to 10 /* diam. 



Hab. On dead leaves, etc. 



16. P. virescens Ditm. — Sporangia sessile, irregularly ovoid, 

 o - 2 to o - 3 mm. diam., much aggregated in confluent groups, rugose, 

 yellowish-green. Capillitium delicate flexuose, lime-knots yellow. 

 Spores pale violet-brown, nearly smooth, 6 to 9 11 diam. 



Van obscurum. Sporangia more scattered, smooth, olive-brown, 

 often forming plasmodiocarps, o'5 mm. diam. 

 Hab. On dead leaves, etc. 



17. P. rubiginosum Fries. — Sporangia sessile, subglobose, 

 o'5 mm. diam., orange or deep red. Capillitium with branching 

 orange lime-knots. Spores pale violet-brown, nearly smooth, 8 to 

 li /x diam. 



Hab. On dead wood and leaves. Rare. 



