1925] Setchell-Gwrdner: Melanophyceae 561 



9. Fronds up to 8 dm. high, 6-8 mm. wide, without distinct lateral veins, stipe 



cylindrical, 3-4 mm. diam 6. D. ligulata (p. 566) 



9. Fronds up to 2.5 m. high and 2 cm. wide, with distinct lateral veins, stipe 



flattened and short 7. D. herbacea (p. 566) 



Section 1. Virides 

 Desmarestia, subgen. Dichloria (Grev.) DeToni. 



Fronds cylindrical or only very slightly compressed ; branching 

 mainly opposite. 



DeToni. Syll. Alg., vol. 3, 1895, p. 456. Dichloria Greville, Alg. 

 Brit., 1830, p. 39. 



1. Desmarestia media (Ag.) Grev. 



Fronds cylindrical, considerably cartilaginous, branching very 

 profusely and opposite throughout ; color dark brown, nearly black on 

 drying; branches of 5-6 orders, each successive order gradually 

 reduced in size, composed of an axial row of relatively large cells sur- 

 rounded by 2-3 layers of large, more or less irregular, elongated cells 

 surrounded in turn by a single palisade layer of cortical assimilating 

 cells, the terminal ramuli long-attenuate and acute. 



Growing on rocks in the upper sublittoral belt. Unalaska, Alaska. 



Greville, Alg. Brit,, 1830, p. xl; Pease, P. S. M. S. Publ., vol. 1, 

 1917, p. 386. Desmarestia aculeata f. media' Setchell and Gardner, 

 Alg. N.W. Amer., 1903, p. 246; Collins, Holden and Setchell, Phyc. 

 Bor.-Amer. (Exsicc), no. 1036. Sporochnus medius Agardh, Sp. Alg., 

 vol. 1, 1820, p. 153, Icones Alg. Ined., 1821, pi. 16. Desmarestia viruiis 

 Saunders, Alg. Harriman Exped. 1901, p. 422 ( ?). 



Desmarestia media var. tenuis S. and G. 



Fronds cylindrical and with opposite branching throughout, very 

 profusely branched, 3-4 dm. high, stipe 2-3 mm. diam., ultimate 

 ramuli very slender and flaccid, 200-250/x diam. ; axial filament of the 

 fronds very large, 100-1 25/^ diam., surrounded by a single layer of 

 large, colorless cells between the axial filament and the small cortical 

 cells. 



Growing on stones, etc., in the upper sublittoral belt. Alaska 

 (Juneau) to Puget Sound, Washington. 



Setchell and Gardner, Phyc. Cont., VII, 1924, p. 7. 



