Didymium. 245 



Didymium Cookci, Raunk., Myx. Dan., p. 109, t. 5, f. 5. 



Physarum tussilaginis, B. and Br., Ann. Nat. Hist., n. 1597; 

 Cke., Myx. Brit., p. 16. 



Chondrioderma Cookci, Host, Mon. App., p. 17. 



Exsicc. Cke., Fung. Brit., Ser. I., 526 (as BadJiamia capsu- 

 lifer); Cke., Fung. Brit., Ser. II., 206; Thura., Myc. Univ., 

 1100; Vize. Micro-fungi Brit,, 1 and 101. 

 (Type in Herb., Kew.) 



On the under surface of living leaves of colts-foot, Tussilago 

 farfara. Britain (Cheshire) ; Denmark. 



A very remarkable species, not agreeing in important points 

 with any established genus, scattered or in groups of 2 4, 

 1'5 3 mm. across. Apparently quite normal in its develop- 

 ment, and not accompanied by any other species, it occurred 

 in abundance for several years in succession in Cheshire, and 

 has also been found in Denmark. In a note attached to the 

 specimens in the Kew Herbarium, Mr. A. Lister says, "The 

 whole appearance conveys the impression that it may not be 

 a stable form, and the habit is so peculiar." Of course it is 

 a matter of opinion as to whether the appearance described 

 above can afford any clue as to stability, but certainly many 

 species occur on living plants. 



The presence of lime in the capillitium prevents the present 

 species from, being a typical Didymium or Chondrioderma ; the 

 lime is too scanty and the capillitium too slender for a 

 Physarum. 



Didymium anomalum, Mass./ 



Plasmodium venulose, arcuate or variously contorted, very 

 convex, surface minutely granulose ; columella very strongly de- 

 veloped, with a broad base resting on the substratum, arcuate, 

 following the shape of the plasmodiocarp ; threads of capillitium 

 very delicate, thin, colourless, flaccid, forming a dense net ; spores 

 minutely verruculose, yellow, 11 13 p diameter. 



Chondrioderma anomalum, Rost., Mon., p. 169 ; Sacc., Syll., 

 1263. 



Russia. 



