188 
Geo. K. Sutherland. 
Sacc. Thus Magnus transferred Microthelia verrucosaria Linds, or 
Didymella verrucosaria Sacc. to Didymosphceria although it possessed 
colourless spores. Similarly Zopf placed Didymosphceria pulposi 
which he found in the apothecia of Collegia pnlposum , in the same 
group. The spores of this species are also colourless. D. 
pelvetiana , just described, occurs under conditions somewhat similar 
to those experienced by the lichen species mentioned above and 
presents corresponding structural characters. Its spores, however, 
become slightly coloured at maturity and thus are more in keeping 
with the generic character than those of the forms included by 
Magnus and Zopf. 
The present inclusion in this genus of many species provided 
with a kind of clypeus seems very unsatisfactory especially when 
it is taken into consideration that this is regarded as sufficiently 
distinctive a character to separate larger groups as in the case of 
the Gnomoniaceae and the Clypeosphaeriaceae. Such anomalies are 
inevitable so long as any attempt is made to place together in a 
purely artificial classification forms which, although in their origin 
and development show natural affinities, differ in the externals on 
which this classification is unfortunately based. 
Didymosphjeria FUCICOLA NOV. SP. 
Mycelium diffusion, perithecia simplicia, sparsa, 120-140// diam., 
globosa vel pyriformia, contextu membranaceo, immersa, ostiolo 
brevissimo atrum pseudo-clypeum perfringente; asci crebri, 70-90//, 
X 10-14//, cylindracei vel clavati, octospori; paraphyses filiformes vel 
apicibus dilatis; sporidia ovoidea, 16-22// x 7-8//, 1-septata, primo 
hyalina demum flavescentia, constricta. 
Hab. In thallo vivo Puci vesiculosi, Orkney. 
Until towards the end of last autumn no external sign of fungoid 
attack had been noted or any species of Fucus, although sections of 
F. vesiculosus, collected earlier in the season, had demonstrated the 
presence of hyphae. Its diffused character doubtless accounted for 
the absence of any obvious trace of damage until comparatively 
late. 
Only when the perithecia appear is it possible to recognise the 
infection without sectioning, and even then it is extremely difficult 
to detect these minute scattered bodies owing to the natural 
blackening of the thallus of the host. 
The mycelium is irregular in thickness, varying from 1'5-2/z, 
and presenting frequently a very much bent and rugged or annulated 
appearance. It also tends to become slightly coloured. Penetrat- 
