1903] Collins, — The Ulvaceae of North America 27 
Frond filiform, compressed, simple or with occasional long pro- 
liferous branches, which usually consist of only two rows of cells; 
cells rectangular, always in longitudinal and mostly in cross series. 
Plate 42, fig. 4, surface view. 
A very slender species, the main filaments only 2-8 cells wide, and 
only in the wider forms showing any open space within. The 
branches are few, at wide angles, and are seldom over two cells wide. 
They resemble somewhat the fronds of Æ. percursa, but the cells in 
the latter are more symmetrically arranged ; and Æ. percursa is always 
simple and never has over two rows of cells, as do most of the 
older parts of this plant. It has been found only once in this country, 
at Eagle Island, Penobscot Bay, Maine, in a lagoon, where the water 
is usually more salt than the sea, with which it connects only at 
very high tides. Here the plant was scattered among Cadophora 
expansa, Lyngbya aestuarii, and species of Lxteromorpha, the 
whole forming a dense mass covering the water for a considerable 
area. Europe. Collins (5) 2; (8) 44. Exsicc. Phyc. Bor.-Am., 
223 
14. E. cRUCIATA Collins (5) 3. Frond filiform, branching, mostly 
of a single series of cells, but at the points of branching often of two 
or more series ; branches issuing at right angles or nearly so, usually 
opposite but sometimes alternate or secund, simple, usually short, 
tapering; monosiphonous portions 20-30 p diameter; cells about as 
long as broad, cell wall thick ; in the irregular masses, where several 
branches issue near together, the cells are rounded and sometimes 
reach a diameter of soy. Plate 43, fig. 1. 
This plant is very different from other species of Zwferomorpa, 
the nearest being Æ. percursa; but Æ. cruciata has nothing of the 
symmetry and uniformity that especially characterize Æ. percursa. 
The monosiphonous parts with few and short branches remind one 
somewhat of RAzzoclonium, but the branches are often of many cells, 
and wherever several branches issue near the same point, an 
irregular mass of cells is formed. The chromatophor is roundish, in 
young plants bright green, in older plants or parts of the plant paler, 
as in other EnferomorfAa species ; the chromatophor does not fill the 
cel. It was found in a lagoon at Eagle Island, Penobscot Bay, 
Maine, in floating masses in company with Cladophora expansa, 
Lyngbya, etc., in July, 1894, and is not known elsewhere. Collins (5) 
3; (8) 44. Exsicc. Phyc. Bor.-Am., 222. 
15. E. Hopxirkit Harvey, Phyc. Brit.; Pl. CCLXIII, 1849; J.G. 
Agardh, Till Alg. Syst., part 3, 151, 1882; Æ. plumosa De Toni, Syll. 
Alg., Vol. I, 132, 1889. Frond filiform, cylindrical or somewhat 
compressed, very slender and delicate, much and repeatedly branched, 
the branches tapering and ending in a single series of cells; cells 
about 8 u wide in monosiphonous part, below about 12 X 20 y, 
with quite small chromatophor, always in longitudinal and often in 
cross series. Plate 43, fig. 3. 
