400 
Notes. 
minute black specks, just visible to the naked eye. On microscopical 
examination, these prove to be the perithecia of a minute Pyreno- 
mycete of a Sphaeria-\.y\>e. They are approximately spherical, and are 
completely immersed in the cortex of the Alga, penetrating only to 
a depth of four cells. The wall consists of a weft of very delicate 
hyphae, and a pore is formed at the surface. The asci are relatively 
large and contain eight elongated spindle-shaped spores, each being 
biseptate by an equatorial division. The mycelium is entirely confined 
to the swollen layers of the cell-walls of the host, and ramifies in great 
abundance in the highly mucilaginous wall-substance of the cells 
forming the inner tissue of the ‘ pod/ 
We have then a definite example of the parasitism of an Ascomy- 
cetous Fungus on one of the Fucaceae. This particular form is 
probably of very general occurrence ; in the neighbourhood of 
Plymouth I have never found Ascophyllum free from it, while material 
from Bangor showed it in equal abundance. It does not appear to 
occur on any of the species of Fucus growing in the same localities, 
nor again on Pelvetia , which extends much further up the tide-mark 
and may not be submerged for days at a time. It may, however, be 
suggested that Ascophyllum is, of all our seaweeds, modified as 
a floating Alga. Its very restricted range, between the limits of the 
neap-tides, together with its elongated buoyed stem, allow it to lie on 
the surface of the tide for the greater part of its existence, and hence 
it might be more exposed to the attack of floating fungus-spores than 
its more shrubby allies. 
ARTHUR H. CHURCH, Oxford. 
