64 
Gen. Isthmoplea, Kjellm. 
I. sphaerophora, Kjellm. Not common. 
Fig.: Harvey I, 93 [as Ectocarpus sphaerophorus]. Plate IX, 18. 
District : Port Erin; Port St. Mary; Castletown; Pooyllvaaish. 
Zone: Same as host. 
Occurrence : Pseudo-perennial. 
Reproduction: Unilocular sporangia in Spring and early Summer ; 
plurilocular sporangia in Summer. 
Notes: Casual in sheltered places generally epiphytic on Plumaria 
elegans and Cladophora rupestris. Most readily recognisable 
by the unilocular sporangia but plants bearing plurilocular 
sporangia only may have been confused with other 
Ectocarpaceae and so have escaped record. 
Gen. Myriotrichia, Harv. 
M. clavaeformis, Harv. Frequent. 
Fig.: Kuckuck (1899), p. 39. 
District : In all districts. 
Zone: Same as host. 
Occurrence: Annual, Summer. 
Reproduction: Unilocular and plurilocular sporangia on the same 
thallus; plurilocular sporangia predominate at beginning 
of Summer, unilocular at the end. 
Notes: First makes its appearance in May or June as an epiphyte on 
other Phaeophyceae (occasionally on Enievomorpha). Host 
plants are frequently Summer annuals, e.g. Chordaria, 
Castagnea, Dictyostphon. Winter form unknown. 
M. filiformis, Harv. Not common. 
Big.) uckuck=(1s909)) pa4oy) later za. 22% 
District : Port Erin; Castletown. 
Zone: Same as host. 
Occurrence: Summer annual. 
Reproduction: See Myriotrichia clavaeformis ; same type of repro- 
duction. 
Notes: Generally found epiphytic on Dictyosiphon foeniculaceus. 
Fam. ARTHROCLADIACEZ. 
Gen. Arthrocladia, Duby. 
A. villosa. Duby. - Rare. 
Fig.: Harvey I, 20. 
District: Fleshwick Bay. 
Zone: Sub-littoral. 
Occurrence : Summer. 
Reproduction : Unilocular sporangia. 
Notes: One record only, dredged. 
