1903] Collins, — The Ulvaceae of North America 25 
ences are probably all due to its place of. growth, — running fresh 
water, Alaska. Exsicc., Phyc. Bor-Am., XXVI; Amer. Algae, 261, 
as Æ. micrococca. 
Forma GLAcrALIS Kjellman, Algenv. Murm. Meeres, 50, 1877. 
Frond 9-13 p thick, cells 5-8 diam.: forming a dense coating on 
rocks covered only at high tide, and at other times wet with water 
from melting ice. Greenland. Rosenvinge (1) 959; (2) 159. 
9. E. compressa (L.) Grev., Algae Brit, 180, Pl. XVIII, 1830, 
excl. var.; J. G. Agardh, Till Alg. Syst., part 3, 137, 1882; De Toni, 
Syll. Alg., Vol. I, 126, 1889. Frond tubular, more or less cóm- 
pressed, sometimes constricted, varying much in dimensions, simple 
or slightly branched; branches usually simple, cylindrical or expand- 
ing above, in either case narrowed at the base, similar in appearance 
to the main frond; cells in no definite order; membrane rather thin. 
Plate 42, fig. 11, surface; fig. 12, cross section. 
A very variable species, but now understood in a narrower sense 
than formerly, and including only forms with branches contracted 
at the base and expanded upwards, with cells about 10-15 a diam., 
arranged in no definite order and with membrane not thickened. It 
occurs all along the Atlantic coast, and from Alaska to San Fran- 
cisco. In New England it appears to be one of the less common 
species. Europe, Brazil, West Indies, Sandwich Islands, Tasmania. 
Farlow (1) 292; (2) 378; (3) 712. Robinson (1) 166. Kjellman 
(2) 52. Collins (1) 245: (8) 44. Ulva compressa var. racemosa 
Kjellman (2) 52. U. Enteromorpha var. compressa Farlow (4) 43. 
Dame & Collins (1) 157. Collins (6) 77. Enteromorpha intestinalis 
var. compressa Rosenvinge (1) 958; (2) 158. Exstcc., Phyc. Bor.- 
Am., 964. 
Forma SUBSIMPLEX J. G. Agardh, Till Alg. Syst, 137, 1882. 
Frond hardly branched, of uniform diameter. So. Harpswell, Maine. 
Exsicc., Phyc. Bor.-Am., 964. 
10. E. MARGINATA J. G. Agardh, Alg. Med., 16, 1842; Till Alg. 
Syst., part 3, 142, 1882 ; De Toni, Syll. Alg., Vol. I, 127, 1889. 
Frond filiform, compressed, simple or with a few short proliferous 
branches; cells 4-8 diam., squarish, arranged in longitudinal 
series, very distinctly in the two or three rows at each side, less so 
in the middle portion. Plate 42, fig. 13, surface. 
A small spécies and apparently not common. It occurs on stems 
and roots of Spartina, etc., at Quincy and Weymouth, Mass., New- 
port, R. L, Bridgeport, Conn., and Atlantic City, New Jersey. 
Inland at Great Salt Lake, Utah. 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 throughout a filament, 
the margin being straight and even. Usually the fronds are simple, 
but occasionally one finds a few proliferous branches. Mediter- 
ranean. Uva marginata Packard (1) 702. Collins (2) 1313 (3) 
