LET 
tanks at the Biological Station where they were epiphytic 
on Cladostephus and on the byssi of Mytilus. They did 
not conform to var. subcylindrica Rosenv. and had 
plurilocular sporangia developed on both sides of the 
filaments and hence did not agree with the description of 
var. uncinatum Rke. It appears therefore that the plants 
are to be referred to var. majus, a variety not hitherto 
recorded for the British Isles. 
6. Sphacelaria. 
The propagules of the genus Sphacelaria are short, lateral 
branches, tapering towards the base, provided with an 
apical cell which divides into three or foursegments. Each 
segment then becomes the apical cell of a branch which thus 
becomes a radiate system of branches any or all of which 
may grow up into erect photosynthetic shoots or into 
rhizoidal filaments according to whether they are uppermost 
or undermost when the propagule leaves the parent plant 
and comes to rest elsewhere. 
7. Spbhacelaria cirrhosa. 
Sphacelaria civrhosa Ag. var. fusca Holm et Batt. is by 
far the commonest species at Port Erin and on the neigh- 
bouring coast. It is particularly conspicuous as a com- 
ponent of the pool flora in the littoral zone where it is 
frequently found epiphytic on Corallina especially in the 
winter when it is most abundant. The variety fusca 
differs from Sphacelaria cirrhosa var. pennata, Hauck, 
which is usually epiphytic on algae from deeper water; as 
for example, Desmarestia aculeata ; it is usually differently 
divided. Var. fusca is less profusely branched and less 
regularly pinnate; it also forms irregular mats or tufts 
from half to one and a half inches in depth, while var. pennata 
_ forms almost spherical tufts on Desmarestia and the fronds 
are quite regularly pinnate or bi-pinnate. Sphacelaria 
civrhosa var. fusca is almost certainly identical with the 
