THE GREEN ALGAE OF NORTH AMERICA 205 



Farlow, 1881, p. 43. Frond simple or having at the base a few 

 branches similar to the main frond, or occasionally a few pro- 

 liferations above ; length varying from a few centimeters to sev- 

 eral meters ; diameter from 1-5 cm. ; at first attached by a 

 short, cylindrical stipe, but soon detached and floating; cylin- 

 drical or expanding above, more or less inflated, often much 

 crisped and contorted, and irregularly and strongly constricted ; 

 cells 10-16 \t. diam., in no regular order; thickness of membrane 

 varying from 50 ^ below to 20 //, above ; cells in cross section 

 from 12 to 30 p.. 



A common and exceedingly variable species, occurring 

 throughout our range except on the southern Atlantic coast, 

 where E. flexuosa appears to take its place ; also in forma tennis 

 in fresh water. There are many intermediate forms that con- 

 nect it with E. compressa, but in its typical form it is distin- 

 guished by the internally thickened membrane, and by the in- 

 testinal appearance, which is indicated by both its generic and 

 its specific names. It is especially a plant of quiet waters, 

 where it sometimes attains enormous dimensions. 



Europe, Brazil, Japan. 



Among the many forms of this species that have been de- 

 scribed, the following have been recognized in America : 



Forma CYLINDRACEA J. G. Agardh, 1882, p. 131 ; P. B.-A., 

 No. 465. Frond long and slender, of uniform diameter; usu- 

 ally floating unattached. Mass, to Conn., Alaska. 



Forma CLAVATA J. G. Agardh, 1882, p. 131 ; P. B.-A., No. 

 966. Frond attached, clavate from a filiform stipe, usually more 

 or less contorted. N. S. to Conn.; Alaska to Cal.; in fresh 

 water, alt. 200 meters, Cal. 



Forma MAXIMA J. G. Agardh, 1882, p. 132; P. B.-A., No. 

 1182. Floating, unattached; inflated and bullate. Me. to N. 

 J.; Alaska. 



Forma TENUIS Collins, 1903, p. 23 ; E. intestinalis Tilden, 

 Amer. Algae, No. 125. Frond attached, clavate from a taper- 

 ing stipe ; membrane thin and delicate, not thickened within. 

 In size and shape of cells and habit of frond, like forma davata 

 of salt water ; the difference in the character of the membrane 

 may be due to the peculiar station, artesian running water. So. 

 Dakota.* 



* This may be the same as E. intestinalis var. crispa Kutzing, 1849, p. 

 478 ; but the description of the latter variety is insufficient to determine; 

 " Phycomate majori inflate undulato-crispo. In aqua dulci." 



