220 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



12. Porphyra tenuissima f Strdmf.) Setchell & Hus. 



Zoe, Vol. V, 1900, p. 68. 



Porphyra tenuissima (Stromf.) Setchell & Hus. Hus, Zoe, Vol. V, 1900, 

 p. 68. 



Diploderma temiissinium Stromf., Bot. Centralbl., Bd. XXVI, 1886, p. 173; 

 Om Algvegetationen vid Islands Kiister, 1886, p. 33. 



Diploderma amplissimiDH f. tenuissima Foslie, Contribution to Knowl- 

 edge of the Marine Algae of Norway, I, 1890, p. 56. 



Porphyra iniyiiata f. tenuissima Rosenvinge, Gr0nlands Havalger, 1893, 

 p. 827; Les Algues Marines du Greenland, 1894, p. 83. 



Wildematiia tenuissima de Toni, Sylloge Algarum, Vol. IV, 1897, p. 23. 



Fronds membranous, 25 cm. long, 14 cm. broad, round-ovate, not lobed, 

 with undulate margin, folded; base cordate, sessile, with small disc; color 

 delicate pink; fronds distromatic, 25,^ thick, except at the base, where they 

 measure 65-75/^1; cells near base square to twice as broad as high, 10-15// 

 broad, cells near edge of frond three to four times as broad as high, 20/^1 

 broad, with rounded angles; surface jelly 2.5//, little jelly between the cells; 

 fronds moncecious, antheridia and sporocarps intermixed in a marginal zone, 

 4 carpospores to each sporocarp, 8 antherozoids to each antheridium. 



The description is drawn from several specimens collected 

 by Mr. de Alton Saunders when with the Harriman Alaskan 

 expedition during the summer of 1899. The study of a 

 large number of specimens of other species of Porphyra has 

 led to the conviction that, to describe a species from but a 

 few specimens is, to say the least, a very unreliable method 

 of procedure; and were it not for the fact that the author 

 had access to a number of European specimens of P. tenuis- 

 sitna, as well as to Stromfelt's ample description (1886), 

 with which the specimen in question agreed in nearly every 

 respect, such a course would not have been undertaken. In 

 matters such as length and breadth of the frond, the evi- 

 dence submitted is of course not conclusive. It must be 

 said that among our specimens are the largest which have 

 as yet come to our notice. The European specimens are 

 less than half the size. In the collection of Porphyra 

 kindly placed at our disposal by Mr. Collins, a specimen 

 was found, collected at Nahant, Massachusetts, which was 

 originally determined as P. leucosticta ' and afterwards 

 designated P. miniata^ but which is evidently P. tenuissima. 



> Bull. Torrey Bot. Club, Vol. IX, 1882, p. 70. 

 2 Bull. Torrey Bot. Club, Vol. XI, 1884, p. 131. 



