144 thp: journal of botany 



This fungus was found in considerable quantity by Mr. Boyd at 

 Dahy, Ayrshire, in July 1919, on Fteris aq^uilliia. It forms small 

 oblong gre\ash spots, running lengthwise of the petioles, and has 

 very much the look of Leptostroma spirceinuui Vest. The spores 

 measure up to 80 or even 90 /x, and are -l-G-septate. (Fig. 10.) 



The interesting point is that, although it is formed, as usual in 

 the group, beneath the cuticle, it shows here and there the appearance 

 which Saccardo attributed to it of "becoming superficial"; but, in 

 ever}^ case, when that part was examined microscopically, it resolved 

 itself into ^^ Didymella Hyphenis (Cooke) Sacc." It seems from the 

 records that, in the localities in which the Leptostromella has been 

 found, the " Didymella " has been associated with it. But there 

 seems here to be a possibility of misconception ; for, in these Scottish 

 specimens, the ascophores are actually immersed in rows in the 

 Leptostromella, which would seem to suggest that they belong, not 

 to a Didymella, but to the Dothideaceae. This must be a false 

 suggestion, however, for the spores and asci are, for the most part, 

 exactly those ascribed to Didymella Hyplienis. 



Further examination disclosed another unexpected fact, viz. : that 

 about 5 per cent, of the ascospores were 3-septate, still remaining quite 

 colourless, a few others being in the intermediate state of having two 

 sejDta. Also an occasional spore was appendiculate at each end, the 

 mucro being about 2 /x long (cf. Didymella lophospora Sacc. & Speg. 

 Syll. i. 561) ; but in both these cases the asci and the size of the 

 spores were all but unaltered. These 3-septate spores might pass as 

 those of Iletaspliceria epipteridea (Cooke & Hark.) Sacc. Syll. ii. 

 183, which has 3-5-septate spores. Didymella Hyphenis would then 

 seem to be merely the younger state of M. epipteridea. 



The apparently dothideaceous condition of Mr. Boj^d's specimens 

 contradicts this idea. But Didymella pteridicola (B. & C.) Sacc. 

 may perhaps be the connecting-link, for that is described as arranged 

 in " little grey parallel lines, covered with the cuticle " (Grevill. iv. 

 145) — a description Avhich at once calls to mind the appearance 

 presented by the Leptostromella when it has the rows of immersed 

 perithecia. It will be noticed that all the fungi so far mentioned 

 are on petioles of Pteris aquiliiia. It may seem bold to suggest 

 that all the six are states or stages of one and the same fungus, yet 

 that is the conclusion which I think will ultimately be drawn. 



A similar increase in septation is now known to occur in many 

 cases. An instance is seen in some specimens of Hhopoyraplius 

 Jiliciims Fckl. which I gathered at Dolgelley in 1887 *. In these, 

 spores having three, four, five, six, or seven septa all occur in the asci 

 indiscriminately, although the normal number is only three (rarely 

 five). The more the matter is examined, the greater number of such 

 cases will undoubtedly be found. 



359. Leptostromella Polypodii, sp. n. 



Pycnidiis angustis, linearibus, rectis, ibseriatis, usque 500 /x longis, 

 50 /x latis, sed ssepe confluentibus, atris, rima apertis. Sporulis 

 linearibus, curvulis, inconspicue guttulatis, hyalinis, 17-25 X 1 /x, 

 sporophoris brevibus, digitaliformibus, ca. 5 X Ij /x, suft'ultis. 



* Rhopographus filiciiius var. cambricus Grove in herb. — Sporidiis 3-7-sep- 

 tiitis, castera typi. 



