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K. MI VA HK 
at the apex while immature but at maturity both serrations and 
sterile piece of leaflet disappear. Sporangial sori, according to 
Okamuka, forming at first ovate or elliptical small patches near 
the base of the sporophylls. Blade lanceolate, tapering gradually 
to the base, somewhat undulate on the magins, with long trans- 
verse corrugations along both sides of the midrib, usually 0.5 m 
in length and 10-23 cm in breadth, somewhat thicker in substance 
as compared with other species; midrib 10.8mm in width, oblong 
in cross section. 
Habitat. Distributed along the coasts from Muroran as far south 
as Hakodate and Sanriku district in Northern Honshu, and often 
menacing the luxuriant growth of Laminaria species by invading 
their substrata. 
3. Alaria yezoensis Mivabe, sp. nov. 
(Plate 23) 
Japanese name. Ainu-wakame. 
Jikkaiso (Nemuro), Kairoppa (Suishö Island off Nemuro Pe- 
ninsula). 
Stipe 3-6 cm in length, subcylindrical below, compressed above; 
rhachis flattened, a part of which bearing sporophylls measures 
only 2.5-3.0 cm in length, while the remaining lower part which 
has shed its sporophylls measures variously according to the age 
of the plant, sometimes attaining to 10-13 cm in length. Sporo- 
phylls 16-24.7 cm in length, 2. 3-3. 0 cm in width, not crowded, long 
linear, rounded and spatulate at the apex, coriaceous, not very 
thick, sori covering the entire surface except along the margin. 
Blade linear oblanceolate, gradually tapering at the base, ca. 2 m 
in length, ca. 15 cm in width, slightly undulate on the margins, 
thin and coriaceous in substance; midrib 1.0-1. 3 cm in width, oblong 
or linear-elliptical in cross section. 
Habitat and use. Distributed along the coasts from Hidaka north- 
eastward as far as Nemuro, and often menacing the growth of 
Laminaria species. Fishing-villagers in Nemuro Province are said 
sometimes to eat sporophylls of this species raw. 
Addenda. None of the known species coincides with the present 
species, so the author proposes here to name it Alaria yezoensis as 
a new species. 
