1920] 8etch€ll-Gardner : Chlorophyceae 253 



Forma maxima J. Ag. 



Frond large, up to 4 cm. diam., inflated and buUate, producing 

 small, scattered branches. 



J. Agardh, Till Alg. Syst., part 3, 1883, p. 132 ; Collins, Green Alg. 

 N. A., 1909, p. 205, Mar. Alg. Vancouver Is., 1913, p. 102 ; Saunders, 

 Alg. Harriman Exp., 1901, p. 411 ; Setchell and Gardner, Alg. N.W. 

 Amer., 1903, p. 212 ; Collins, Holden and Setchell, Phyc. Bor.-Amer. 

 (Exsicc), no. 1182. 



Forma clavata J. Ag. 



Frond always attached, filiform below, enlarging more or less 

 abruptly upwards, open at the upper end, 1-5 cm. wide, 1-5 dm. long. 



J. Agardh, Till Alg. Syst., part 3, 1883, p. 131 ; Collins, Green Alg. 

 N. A., 1909, p. 205, Mar. Alg. Vancouver Is., 1913, p. 102. Entero- 

 morpha intestinalis f. genwina Hauck, Meeresalg., 1885, p. 426 ; Setchell 

 and Gardner, Alg. N.W. Amer., 1903, p. 212 ; Tilden, Amer. Alg. 

 (Exsicc), no. 263. 



There appears to be no authenticated type specimen of the Ulva 

 intestinalis of Linnaeus in existence (cf. Jackson, B. D., 1912, p. 147), 

 so that we must follow general tradition as to the nature of this 

 species. As generall}^ agreed upon, it possesses a tubular frond usually 

 inflated, of varying length and diameter, often twisted or constricted, 

 usually branched from a slender base, occasionally slightly proliferous 

 above, and with the rather large, angular or slightly elongated cells 

 not arranged in longitudinal rows, at least not in the adult frond. 

 Under this conception are arranged many and seemingly diverse 

 forms both as to shape and size. The most slender plants of f. cylin- 

 dracea, e.g., may not be much over 1 or 2 mm. in greatest diameter, 

 while the largest of f. maxima, on the contrary, may be 10 cm. through. 

 In regard to amount of inflation, smoothness or rugosit^y of surface, 

 constriction or lack of it, and even of thickness or thinness of the 

 membrane itself, there is much difference between specimens seemingly 

 correctly referred to Enteromorpha intestinalis. What these very 

 diverse forms indicate needs cultural experimentation to demonstrate. 

 At present, we assume an identical genetic constitution for all and hold 

 the varjang environmental conditions responsible for transformations 

 of form. This method is very unsatisfactory, but it is the best that 

 can be done at present. Even with the wide range of characters we 

 have given to the species, we have, nevertheless, followed the more 



