1903] Collins, — The Ulvaceae of North America 23 
6. E. INTESTINALIS (L.) Link, Epist. in Hor. Phys. Berlin, 5, 1820; 
J. G. Agardh, Till Alg. Syst., Part 3, 131, Pl. IV, Fig. 109, 1882; De 
Toni, Syll. Alg., Vol. I. 123, 1889. Frond simple or having at the 
base a few branches similar to the main frond, or occasionally a few 
proliferations above; length varying from a few centimeters to several 
meters ; diameter from 1—5 cm. ; at first attached by a short cylindrical 
stipe, but soon detached and floating; cylindrical or expanding above, 
more or less inflated, often much crisped and contorted, and irregu- 
larly and strongly constricted; cells 10-16 » diam., in no regular 
order; thickness of membrane varying from so p below to 20 p above; 
cells in cross section from 12 to 3o p. Plate 42, Fig. 6, surface; fig. 7, 
cross section. 
A common and exceedingly variable species, occurring throughout 
our limits except on the southern Atlantic coast, where Z. flexuosa 
appears to take its place. There are many intermediate forms 
that connect it with Æ. compressa, but in its typical form it is 
distinguished by the internally thickened membrane, and by the 
intestinal appearance, which is indicated by both its generic and its 
specific name. It is especiallya plant of quiet waters, where it some- 
times attains enormous dimensions. Europe, West Brazil, Indies, 
Japan. Harvey (1) 57, in part. Eaton (1) 348. Farlow (1) 
292; (2) 378; (3) 712. Wood (1) 183. Robinson (1) 166. 
Hervey (1) 50. Hall (1) 112, in part. Rosenvinge (1) 957; 
(2) 157; (3) 117. Collins (7) 245; (8) 44. Saunders (1) 411. 
Ulva Enteromorpha var. intestinalis Farlow (4) 43. Hay & MacKay 
(1) 63. Collins (4) 310; (6) 77. Dame & Collins (1) 157. Bennett 
(1) 95. Martindale (1) 92. Howe (1) 67. Exsicc. PhydPBor.. 
Am., 464. Amer. Algae, 263. 
Among the many forms of this species which have been described, 
the following have been recognized in America.  ‘* 
Forma CYLINDRACEA J. G. Agardh, Till Alg. Syst., part 2 131, 
1882. Frond long and slender, of uniform diameter. Newport, R. 
I., Bridgeport, Conn., floating unattached. Saunders (1) 411. 
Collins (8) 44. Exsicc. Phyc. Bor.-Am., 465: Amer. Alga, 126. 
Forma cLavata J. G. Agardh, l. c. 131. Frond attached, clavate, 
from a filiform stipe, usually more or less contorted. Cutler, Maine; 
Alaska. Exsicc. Phyc. Bor.-Am., 966. 
Forma MaxiMa J. G. Agardh, l. c. 132. Frond floating, unat- 
tached, inflated and bullate. In quiet waters, Mass., Conn., N. J., 
Alaska. Saunders (1) 411. Collins (8) 44. 
Forma tenuis n. f. Membrane thin and delicate, not thickened 
within. Artesian running water, Redfield, So. Dakota. Amer. 
Algae, 125. In size and shape of cells and in habit of frond, this 
form agrees with forma c/avata of the coast. The difference in the 
character of the membrane may be due to the peculiar station. 
7. E. Linza (L.) J. G. Agardh, Till Alg. Syst., part 3, 134, Pl. IV, 
