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



2. E. CRUCIATA Collins, 1896, p. 3 ; 1903, p. 27, PI. XLIII, 

 fig. i ; P. B.-A., No. 222. 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 secuncl, simple, 

 usually short, tapering ; rnonosiphonous portions 20-30 // diam- 

 eter ; 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 50 p. 



This plant is very different from other species of Enteromor- 

 pha, the nearest being E. percursa ; but E. cruciata has nothing 

 of the symmetry and uniformity that especially characterize 

 E. percursa. The monosiphonous parts with few and short 

 branches remind one somewhat of Rhizodonium, but the 

 branches are often of many cells, and wherever several 

 branches issue near the same point, an irregular mass of 

 cells is formed. It was found in a lagoon at Eagle Island, 

 Penobscot Bay, Maine, connecting with the sea only at excep- 

 tionally high tides, in floating masses in company with Clado- 

 phora expansa, Lyngbya, etc., in July, 1894, au d is not known 

 elsewhere. 



3. E. TORTA (Mert.) Reinbold, 1893, p. 201 ; P. B.-A., No. 

 223. Frond filiform, compressed, simple or with occasional long 

 proliferous branches, which usually consist of only two row y s of 

 cells ; cells rectangular, always in longitudinal and mostly in 

 cross series. Me., Barbados. Europe. 



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 E. percursa, 

 but the cells in the latter are more symmetrically arranged ; and 

 E. percursa is always simple and never has over two rows of 

 cells, as do most of the older parts of this plant. 



4. E. PLUMOSA Kiitzing, 1843, p. 300, PI. XX, fig. i ; E. 

 Hopk/'rkii Harvey, 1849-51, PI. CCLXIII ; 1858, p. 58; P. 

 B.-A., No. 463; Ulva Hopkirkii Farlow, iSSi, p. 44. 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 p. 

 wide in the monosiphonous part, below about 1 2 X 20 /u,, with 



