(l8S) A NEW JAPANESE PRASIOLA. 



From the diagnoses of De-Toni* and VVoUef it seems that this species is 

 nearly allied to P. mexicana, Liebm. 



This alga grows in rapid streams in mountainous parts of the country. 

 My specimens are from Nikko (province of Shimotsuke), Kiriu (Kozuke), 

 Shibakawa (Suruga), and Oimura (Mino). The ravine known as the 

 Daiyagawa, .at Nikko, is well known as one of the localities where this alga 

 grows abundantly. The specimens figured are two of those kindly collected for 

 me by Mr. I. Ogasawara. He sent to me early in March, 189 1, a stone 

 about 30 cm. in diameter, on which was growing a number of this alga. 

 The stone was taken from the Kiriu-gawa, a rapid stream near the town of 

 Kiriu. 



In the districts where this alga grows people collect it in large quantities 

 especially in autumn, press and dry it into the form of quadrangular sheets, and 

 sell them as an article of food under the names different in various localities, 

 such as Kaiua-nori, Shibakawa-norl, Daiyagawa-nori, &c. They are eaten 

 either slightly broiled or vinegared after putting them in water. The sheets 

 sent from Kiriu are 32 cm. long and 26 cm. broad; those from Shibakawa, 48 

 cm. long and 28 cm. broad; those from Nikko, 48 cm. long 34 cm. broad. 

 They are not so commonly sold at shops as the sheets similarly prepared from 

 Porphyra and Enteromorphay common forms of alga in the shallow sea. 



According to Mr. I. Ogasawara who has written to me in regard to this 

 alga, it is generally about 10 cm. long, but larger specimens are 20 cm. or 

 more long. It can be collected from the time of the year when the frost first 



'^De-Toni, Sylloge Algarum, vol. i., p. 143. 

 t Wolle, Fresh- Water Algae, p. 107, t. 91. 



