THE GREEN ALGAE OF NORTH AMERICA 303 



i. D. PLUMOSA (Vauch.) Agardh, 1812, p. 42; Harvey, 

 1858, p. 72; Wolle, 1887, p. 109, PL XCIV; Hazen, 1902, p. 

 218, PL XL, figs, i and 2; P. B.-A., Nos. 21, 1224. Tufts up 

 to 15 cm. long, branches spreading or ascending, solitary or 

 opposite, fascicles of ramuli single, opposite, or whorled, usually 

 erect, dense, lanceolate or ovate-acuminate in outline, with pro- 

 longed percurrent rachis ; ramuli erect or ascending, subulate 

 or setiferous ; cells of main filaments and branches subcylindri- 

 cal, 45-70 /Ji diam., 1-3 diam. long; ramuli 6-10 ^ diam., 1-4 

 diam.Jong; chromatophore occupying ^-^i the length of the 

 large cells, proportionately broader in the smaller cells. Ver- 

 mont to California. Europe. 



A widely distributed and fairly common species ; its most 

 distinctive character is found in the dense, plumose fascicles of 

 ramuli, acuminate in outline, with percurrent rachis. 



2. D. ACUTA (Ag.) Kiitzing, 1845, p. 230; 1853, PL XIII, 

 fig. 2; Hazen, 1902, p. 219; P. B.-A., No. 1072. Tufts up to 

 10 cm. long, branches spreading or ascending, solitary or oppo- 

 site, fascicles of ramuli single, opposite, or whorled, somewhat 

 dense, ascending or spreading, broadly ovate to lance-ovate and 

 acuminate in outline, rachis usually distinct ; ramuli ascending, 

 often curved, subulate or setiferous ; cells of larger branches 

 somewhat inflated, or nearly cylindrical above, 50-90, rarely 

 no p. diam., 1-2 diam. long; chromatophore not over half the 

 the cell length in width ; ramuli 6-10 (j. diam. Mass, to N. J., 

 Oregon. Europe. 



Quite close to D.pliunosa, and perhaps only a variety, but 

 usually with larger stems, branching more spreading, fascicles 

 of ramuli broader in outline. 



3. D. GLOMERATA (Vauch.) Agardh, 1812, p. 41 ; Harvey, 

 1858, p. 72 ; Wolle, 1887, p. 108, PL XCII ; Hazen, 1902, p. 

 220, PL XL, figs. 3 and 4; P. B.-A., No. 20. Tufts usually 

 dense, up to 8 cm. long ; filaments much branched, branches 

 spreading or horizontal, solitary or opposite, moniliform, bear- 

 ing very numerous scattered, opposite, or whorled fascicles of 

 ramuli ; fascicles mostly set at right angles to the stem and 

 sessile, broadly orbicular to elliptical, rachis indistinct, ramuli 

 spreading, crowded, subulate, often long-setiferous ; cells of 

 main branches much swollen, 50-90 or even 125 /JL diam., *4-2 

 diam. long; chromatophore here not over half as broad as the 

 length of the cell, but proportionally broader in the smaller 

 branches ; ramuli 6-9 i*. diam. Fig. 89. Maine to N. J., Minn., 

 Cal. Europe. 



