26 Rhodora [JANUARY 
310; (8) 44. Martindale (1) 93. Britton (1) 400. Exsicc., Amer. 
Algae, 266; Phyc. Bor.-Am., 466. 
11. E. crintra (Roth) J. G. Agardh, Till Alg. Syst., part 3, 145, 
1882; De Toni, Syll. Alg., Vol. I, 129, 1889. 
Frond filiform, cylindrical or compressed, much and repeatedly 
branched, the branches tapering, thé smallest usually of a single 
series of quite short cells; cells almost always in longitudinal series, 
often rounded, nearly or quite filled by the chromatophor. Plate 42, 
fig. 14, surface view with monosiphonous branch. 
In habit this species is much like Æ. c/athrata, especially the 
var. rostrata ; but the latter lacks the short-celled monosiphonous 
ramuli; monosiphonous ramuli are found in Æ. Hopkirkii, but the 
net-like cells of the latter are quite distinct from the cells of Æ. crinita, 
which resemble those of Æ. prolifera, though somewhat smaller. 
'Their typical forms are of different habit; intermediate forms are, 
however, provokingly common. It occurs along the New England 
coast and from San Francisco, Cal., to Alaska; according to Agardh, 
in the Gulf of Mexico; it probably extends over the coasts of both 
sides of the continent; Atlantic shores of Europe; Red Sea. Collins 
(5) 2; (8) 44. Saunders (1) 412. Æ. clathrata var. crinita Martin- 
dale (1) 93. Britton (1) 4or. Exsicc, Phyc. Bor.-Am., 460, 965. 
12. E. PERCURSA (Ag.) J. G. Agardh, Alg. Med., 15, 1842; X. 
percursa var. simpliciuscula, Till Alg. Syst, part 3, 146, 1882! ; De 
Toni, Syll. Alg., Vol. I, 146, 1889, in part. 
Frond filiform, in the earliest state of one row, afterwards of two 
rows of cells, placed symmetrically side by side; cells 10-15 a wide, 
from once to twice as long. Plate 42, fig. 15, young filament; fig. 
16, mature filament. 
A common species, forming masses in upper tide pools, and in 
ditches in marshes, etc. It often grows in company with other spe- 
cies, but is easily distinguished on microscopic examination by the 
double row of cells, usually in exact symmetry, side by side. The 
small chromatophors occupy only part of the cell room, giving the 
same net-like appearance found in Æ. clathrata. It is found from 
Greenland to New Jersey, and from Alaska to California; it is 
apparently a summer plant. Europe. Collins (8) 44. Tetranema 
percursum Collins (7) 244. Percursaria percursa Rosenvinge (1) 
963; (2) 160; (3) 118. | Ulva percursa Collins (2) 31; (3) 310. 
Martindale (1) 93. Britton (1) 401. Exsicc, Alg. Am.-Bor., 219; 
Phyc. Bor-Am., 469, 968 
13. E. rorta (Mert.) Reinbold, Nuova Notarisia, series 4, 201, 
1893. Æ. percursa var. ramosa J. G. Agardh, Till Alg. Syst., part 3, 
146, 1882. 
1 The Æ. percursa of J. G. Agardh, |. c. 146, appears to include at last two 
species; for a full discussion of the question see Reinbold, Nuova Nota- 
risia, Series IV, 201, 1893. 
