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NOTES ON BRITISH MYCETOZOA. 

 By Arthur Lister, F.L.S. 



Crateriachea mutabilis Rost. This species was found in abun- 

 dance on Aug. SOtli, 1895, spreading over a scattered heap of 

 Senecio Jacohiea, which had been weeded out of a meadow and 

 thrown down under the shade of tall trees at Wardonr Castle, 

 "Wilts. The rooting leaves and herbage were crowded besides with 

 other Mycetozoa, chiefly with Phymrnm cinerenm Pers., Bidtjmium 

 nif/ripes Fr. var. .ranthnpus, and D. diff'orme Duby. The Crateriachea 

 closely corresponds with the type specimen in the Strassburg col- 

 lection, consisting partly of white ovoid sporangia standing erect on 

 an ochraceous hypothallus, and partly of elongate plasmodiocarps 

 either single or combined into an irregular net. The sporangia 

 are sessile, or the hypothallus is produced into a stalk, which 

 merges into the persistent base of the sporangium-wall. The 

 capillitium consists of a rigid network of hyaline threads, with 

 broad expansions at the anglps. The lime-knots are strongly de- 

 veloped, and are chiefly confluent in the centre of the sporangium, 

 forming a clavate pseudo columella, which is either free or 'gttached 

 to the base of the sporangium-wall. When the fragile upper wall 

 falls away, and the spores are dispersed, the persistent capillitium 

 encircling the white columella bears a considerable resemblance, 

 under a low magnifying power, to the empty sporangia of DiachcBa 

 eleijans Fr. In many instances, however, the lime-knots are mox"e 

 equally scattered throughout the capillitium, and are confluent 

 only to form a small irregular central mass. 



We have represented in this fine gathering the form named 

 Diil;/)iiivm, neapoHtamim by Cesati, and collected by him in the 

 Naples Botanical Gardens; and also the very similar form gathered 

 by Bizzozero in April, 1883, in the Botanical Gardens, Pavia, and 

 distributed by Rabenhorst and Winter under the name of D. sqnamii- 

 losum. var. herbarum. These two specimens are referred to in the 

 British Museum Catalogue of Mycetozoa, p. 56, in the note to 

 Physarum cinereum. Their similarity to some forms of that species, 

 and also to the Strassburg type of Crateriachea, suggested that, until 

 further gatherings were obtained establishing their stability, it was 

 a question whether they, together with Crateriachea, might not 

 prove to be merely varieties of Phymrum cinereum. The present 

 gathering clears up this point, showing that they are all forms of 

 one distinct species, of wliicli the type is Crateriachea )nutabilislXost. 

 The purple-brown spinulose spores. 8 // diara., are alike in all, and 

 the more globose sporangia and scattered lime-knots of the Italian 

 specimens are repeated in parts of tlie Wardour Castle gathering. 

 When, however, we search for characters wliich would warrant the 

 placing Crateriachea in a separate genus, we fail to find them. It 

 is clearly embraced in the genus Physarum as at present constituted, 

 and naturally takes its place between P. didermoides and P. cinereum. 

 The most striking feature, viz., the large development of the pseudo- 

 columella, is not exceptional in the genus ; it frequently occurs in 



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