202 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



coating on rocks covered only at high tide, and at other times 

 wet with water from melting ice. Greenland ; Mass. 



The habitat given with the description is that of the original 

 arctic locality ; the Mass, specimens agree with the Greenland 

 plant, though growing in summer, free from glacial conditions. 



12. E. SAUNA Kiitzing, 1845, p. 247; 1856, p. 13, PI. 

 XXXVI, fig. r ; P. B.-A., No. 659. Frond filiform, tubular, 

 with a few branches, which are sometimes opposite, of two or 

 more rows of cells, or in the youngest of a single series ; cells 

 quadrangular, 14-16 p. square, or slightly longer than broad, in 

 longitudinal series throughout ; membrane thickened on both 

 sides. Fla., Louisiana. Europe- 



The slender fronds with relatively large cells in longitudinal 

 series distinguish this species with tolerable distinctness from 

 any others within our limits. 



Var. POLYCLADOS Kiitzing, 1845, p. 248; E. poly dados Kiit- 

 zing, 1856, p. 13, PI. XXXVI, fig. 2. Filaments beset with 

 more or less numerous short, horizontal, spine-like rarnuli. 

 Florida. 



13. E. MARGINATA J. G. Agardh, 1842, p. 16 ; Kiitzing, 

 1856, p. 15, PI. XLJ, fig. i; P. B.-A., No. 466. Frond fili- 

 form, compressed, simple or with a few proliferous branches ; 

 cells 4-8 p. diam., squarish, arranged in longitudinal series, very 

 distinctly in the two or three rows at each side, less so on the 

 middle portion. Me. to N. J. ; Great Salt Lake, Utah; Cal. 



Europe. 



A small species and apparently not common, occuring mostly 

 on stems and roots of Spartina, etc. The color is usually quite 

 a deep green ; the fronds are comparatively narrow, seldom over 

 15-20 cells wide, and the width continues quite uniform through- 

 out a filament, the margin being straight and even. Usually 

 the fronds are simple, but occasionally one finds a few prolifer- 

 ous branches. 



14. E. PROLIFERA (Fl. Dan.) J. G. Agardh, 1882, p. 129, 

 PI. IV, figs. 103 and 104; P. B.-A., Nos. 470,610, 913. Frond 

 up to several meters long and 2 cm. diameter, tubular or com- 

 pressed, with more or less abundant proliferous branches, 

 which are usually simple, but sometimes also proliferous ; 

 branches varying much in length and diameter; cells 10-12 /A, 

 in the younger parts always arranged in longitudinal series, 

 which become less distinct in the older parts; membrane 15-18 



