336 Transactions British Mycological Society. 



into the surrounding cells. The spores, which are formed inter- 

 calarily upon the hyphae, are dark brown and possess a thick, 

 firm, smooth membrane. The mature spores measure about 22- 

 23-3/u. across their longest diameter. Often they are completely 

 spherical but at other times they may measure 23-3 x 20'6/x, 

 23-3 X I9-2/X, or even 22-3 x 17-8/^ across their longest and 

 shortest diameters respectively. 



Besides the species mentioned above there are three others 

 which have provisionally been placed under Melanotaenium but 

 probably belong elsewhere. Of these, one is M. Sparganii which 

 grows upon the leaves of Sparganium and possesses spores mea- 

 suring 10-16 X g-iOju, in diameter and which are yellow-brown 

 in colour. It was first described by Lagerheim (1899) and is 

 probably more correctly to be referred to the Chytridiaceae. 



Another doubtful form is M. maculare (Wallr.) Cornu. This 

 occurs within the epidermal cells of the leaves of Alisnia ranun- 

 culoides var. repens, and was first described by Wallroth as 

 Physoderma maculare and provisionally referred to Melanotae- 

 nium by Cornu (1883). It forms small black spots upon the leaf 

 but produces no swelling or hypertrophy of the tissues. This is 

 almost certainly not a Melanotaenium and Wallroth's original 

 name may be retained for it. 



A third form which has been dubiously included under Me- 

 lanotaenium by Cornu (1883) is M. scirpicolum Cornu. This 

 occurs upon the rhizome of Scirpus lacustris. Its spores are ovoid, 

 pale brown in colour and measure 28-32 x 18-20/i, in diameter. 



The foregoing appears to be a complete list of all the species 

 of Melanotaenium which have hitherto been described and it re- 

 mains to see what relationship the parasite upon Lamiuni album 

 bears towards them. 



Spore 

 Species Host measurement 



M. cingens (Beck) Magnus Stems and leaves of Linaria 12-18 /x 

 (Syn. M. cmilium Schr.) vulgaris and L. genistifolia 



M. hypogaeum (Tul.) Schel- Hypocotyl and root of Lina- 14-22/i 

 lenberg ria spuria 



M. endogemim (Unger) de Stems and leaves of Galium 16-22/i 

 Bary spp. 



(M. Ari (Cooke) Lagerheim Leaves and petioles of Arum 14-16/a) 



niacidatum. 



M. Selaginellae Henn. et Stem and leaf bases of 5e/a- 17-ig/M 

 Nym. ginella 



M. Jaapii Magnus Stem and root of Teucrium 17-8-23(1 



montanum 



M. Lamii, sp. nov. Subterranean stems and buds iy-20 fi 



of Lamium album 



The points in which the species are differentiated from one 

 another are very slight and dependence has been chiefly placed 



