Presidential Address. T. Petch. 33 
throughout the tropics, forms black, irregular stromata over or 
at the side of the scale, and often extending some distance from 
it. Thisis Myriangium. The stroma is parenchymatous, without 
true perithecia, but with asci embedded singly in the tissue. 
The spores are muriform. It was first recorded on scale insects 
by Zimmermann* in Java in Igor, and has since been found 
on them in Ceylon, Florida, the West Indies, etc. Some doubt 
has been expressed concerning the parasitism of this group, 
because it frequently occurs in company with Sphaerostilbe, 
but the explanation of that would appear to be that it attacks 
the same species of scale insects as the latter. In many instances 
it is the only fungus present. 
Mr Ramsbottom has pointed out to me that Myriangium has 
been known to be a British genus for more than half a century, 
though it has not been included in lists or textbooks of British 
fungi. When Berkeley described the genust, he stated that it 
was allied to Collema; hence it was at first included among the 
lichens. Subsequently, it was discarded by the lichenologists, 
and the mycologists omitted to take it up. Specimens of 
Myriangium were collected in abundance during the Foray on 
Chionaspis salicis on Ash, and effete stromata have been 
gathered on the same host in Norfolk and Yorkshire. 
It is customary to refer the species of Myriangium found on 
scale insects to Myriangium Duriaei Mont. and Berk., the type 
species of the genus, originally recorded in 1845 from the 
Pyrenees, Algeria and Australia, but the examination of the 
numerous gatherings of this genus now available has not yet 
been completed. Myriangium Acaciae McAlp. is entomogenous. 
Myriangium is generally placed in the Plectascineae, in the 
subfamily Myriangiaceae. Von Hohnel}, who has recently re- 
vised the subfamily, considers that the latter should be placed 
in the Dothideales. Myriangiaceae has been a convenient centre 
for little-known genera of doubtful affinities, and von Hohnel 
has found it necessary to reduce the 23 genera hitherto included 
in it to five, either by synonymy or exclusion. Apparently 
I2 species now remain in Myviangium. It remains to be deter- 
mined how many of these are valid, how many are entomo- 
genous, and whether any of the other genera of Myrzangiaceae 
which have superficial stromata are entomogenous. 
As recorded by Parkin§, a black stromatic fungus, somewhat 
resembling Myriangium, but pycnidial, is found on Mytilaspis 
in Ceylon. It usually has prominent pycnidia, which contain 
small, brown, narrow-oval spores. Parkin suggested that this 
* Ob. cit., supra. + Hooker’s Lond. Journ. Bot., 1v (1845), Pp. 74. 
} Fragmente zur Mykologie, v1 Mitt. (1909), pp. 75-102. 
§ Op. cit., supra. 
M.S. 3 
