Additional Notes on Marine Pyrenomycetes. 189 
ing between the cell walls, it finds an easy passage towards the 
central tissues, through the radial linear series of cells forming the 
cortex. So far, no haustoria have been observed, although the 
broken-down appearance of encircled cells would indicate the 
presence of some form of absorptive organ. 
The young perithecia and accompanying pseudo-clypei arise 
very much as has been described already for Didyniosphceria 
pelvetianu. The masses of fine thin-walled hyphae, at first irregular 
in outline and without any distinct limiting layer, force the sub- 
epidermal cells of the host apart, breaking down those in their imme¬ 
diate neighbourhood. Gradually the peridia become differentiated, 
and the ostioles, already blackened, break an opening through the 
pseudo-clypei, but without projecting. This is followed by a slow 
darkening of the outer membranous layer of the walls inside which 
soft hyaline hyphae form a lining from 15-20/x thick. These globose 
or flask-shaped perithecia are slightly larger than in the species on 
Pelvetia and are confined mainly to the persistent thickened midrib 
portions or so-called stalks of older specimens. They contain 
bunched together on the basal cushions a large number of cylindrical 
or clavateasci interspersed with numerous filamentous paraphyses. 
The former are thick-walled at first, but, after the differentiation of 
their contents into spores, their walls become thin, though remaining 
tenacious. The ascospores are ovoid. Their broad upper and 
narrow, tapering lower ends, separated by a distinct constriction, 
distinguish them from the usually longer fusiform spores of D. 
pelvetiana. Like the latter they become slightly coloured at 
maturity. 
The perithecia appear late in autumn and rarely reach full 
maturity before October. 
Smaller fruiting bodies were observed in many of the sections. 
These differed in shape from the perithecia just described and lacked 
their characteristic coverings. In habit and structure they resembled 
the pycnidia of Stigniatea but, as no pycnidiospores were found, it 
is impossible to state definitely whether they are pycnidia or merely 
imperfectly developed perithecia. 
It is interesting to note the frequent occurrence of a species 
.of Elachista along with the fungus just as in Pelvetia , but here 
again no connection has been established between the two. 
Although this species presents a striking resemblance to D. 
pelvetiava, the differences in the size of the perithecia and the 
asci, and in the shape of the ascospores justify their separation. 
