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



19. E. LINZA (L,.) J. G. Agardh, 1882, p. 134, PL IV, figs. 

 110-112; P. B.-A., Nos. 16,967; Ulva linza Harvey, 1846-51, 

 PL XXXIX ; 1858, p. 59 ; U. enteromorpha var. lanceolata Far- 

 low, 1 88 1, p. 43. Frond lanceolate or linear-lanceolate, simple, 

 1-5 dm. long, 1-20 cm. broad; stipe short, hollow; upper part 

 of the frond flat, the membranes grown together as in Ulva, ex- 

 cept at the edges, where they remain free. Me. to W. I.; 

 Alaska to Cal. Europe, So. America, Tasmania. 



The forms of this species are divided by J. G. Agardh under 

 forma crispata, with edges much crisped and folded, and forma 

 lanceolata, edges even or plicate, not crisped. In one or the 

 other of these forms the species seems common on the whole 

 coast of the U. S.; whether extending farther south is not cer- 

 tain. It grows on stones, woodwork and other algae, usually 

 in places seldom or never left bare by the tide. The smaller 

 forms look like forms of E. intestinalis, but in the latter the 

 frond, though often collapsed, is tubular throughout ; in E. 

 linza the two membranes adhere, except at the edges, where 

 there is a narrow open space, around which the cells are 

 arranged, in cross section nearly in a circle. 



2. ILEA Fries, 1825, p. 336. 



Frond filamentous, hollow, gelatinous, the cells mostly in twos 

 and fours, enclosed within the wall of the mother cell, and 

 arranged in distinct longitudinal series, the series loosely con- 

 nected laterally. 



Only one species. 



I. PULVESCENS (Ag.) J. G. Agardh, 1882, p. 115 ; P. B.-A., 

 No. 264; Enteromorpha aureola Kiitzing, 1856, p. 14, PL XL/, 

 fig. 3. Characters of the genus. Fig. 71. Me. to N. J.; 

 Alaska. Europe, So. Pacific. 



This plant grows in dense tufts, the filaments usually 5-20 

 cm. long, the diam. being seldom over 2 mm., but specimens 

 have been found one meter long, 2 cm. diam. The fronds are 

 soft and gelatinous, the color varying from dark green to brown- 

 ish or yellow. The cells have a distinctive Gloeocapsa-like 

 arrangement, and are in longitudinal series so distinct that by 

 pressure on the cover glass they readily separate, appearing 

 like free filaments of one or two cells wide. 



It grows best in places where streams of fresh water empty 



