30 
K. MIYABE 
4. Costaria Greviere 
Greville, Algae Britannicae, p. xxxix, 1830. 
The genus Costaria is characterized by having a blade traversed 
by five longitudinal ribs, of which the central and two outermost 
ones are all projecting on the same surface of the blade but are 
depressed on the other while the remaining two intermediate ones 
are projecting on the opposite surface as compared with the other 
three. The numerous small perforations are scattered all over the 
blade. The surface of the blade is adorned with gyrate puckerings, 
and also, while young, with cryptostomata. Mucilage ducts are 
absent from both stipe and blade. Sporangial sori are formed from 
the basal part of the blade upward, mostly within the depressed 
portions of both upper and under surfaces of the blade, sometimes 
spreading over the elevated portions. Stipe is provided on the 
surface with more than ten longitudinal projecting striations. 
De Toni, in his Sylloge Algarum (Vol. Ill, 1895), placed four 
species in the present genus. However, judging from the fact 
that Costaria Turneri in Hokkaido is variable in the morphology of 
the thallus according to the topography of the habitat, Costaria 
Mertensii J. Ao. and C. quadrinervia Ruck, are considered to be 
nothing but varietal forms or malformed individuals of C. Turneri 
Grev. The remaining Costaria reticulata Saund. is not to be placed 
in this genus. r ' 0) Then the genus Costaria would be regarded as 
consisting of a single species. 
Costaria Turneri Grevirre 
(P late 20j 
Greville, Algae Britannicae, p. xxxix, 1830. 
Illustration. Turner, Historia Fucorum, Vol. IV, Tab. 226, 1819 ; POSTELS et 
Ruprecht, Illustrationes Algarum, Tab. XXIV, 1840. 
Japanese name. Zarame. 
Zarame (Kushiro, Etorofu), Zarume (Osatsube & Todohokke), 
Sujime (named by Dr. Okamura), Jarame (Hakodate), Aname (Riku- 
chü Province in Honshu), Kagome (Kiritappu & Nemuro), Arame- 
kombu (Kitami-mombetsu). 
30) Costaria reticulata ? SAUNDERS (1895, p. 58, tab. VII) is known to be a young 
stage of Diclyoneuron calif 'or nicum Rupr. [Cf. SetchELL and GARDNER, 1925, 
p. 610). 
