360 University of California Publications. [botany 



and Port Clarence, Alaska, Kjellman (1889, p. 21); St. Paul 

 Island, Alaska, Setchell (1899, p. 595); west shore of Amaknak 

 Island, Bay of Unalaska, Alaska, W.A.S. and A.A.L., No. 

 3242!; Unalaska, Alaska, Postels and Ruprecht (1840, p. 20, 

 under Corallina cretacea) ; near Iliuliuk, Unalaska, Alaska, 

 W.A.S. and A.A.L., Nos. 4093!, 4075!; Uyak Bay, Kadiak 

 Island, Alaska, W.A.S. and A.A.L., No. 5088! ; Port Renfrew, 

 B. C, Tendo (1902, p. 714). 



This species is to be distinguished from the forms of the next 

 by the fact that its joints are always cylindrical and never flat- 

 tened in any portion of the frond. We have not attempted to 

 distinguish between the forms, but we agree with Yendo that 

 Amphiroa Tasmanica Kuetzing is probably but a form of this 

 species and that it, or a similar form, occurs in our territory. 

 Of the plants accessible to us and enumerated above, Nos. 3242 

 and 4075 are the typical form; No. 4093, which is from water 

 of 10 fathoms in depth, agrees with the f. Tasmanica Yendo ; 

 while No. 5088 shows specimens of both forms growing inter- 

 mixed. 



Amphiroa tuberculosa (P. & R.) Endlicher (in extended sense). 



After a long study of the forms of Amphiroa with flat- 

 tened joints from the western coast of North America, we 

 have come to the conclusion that they are all forms of one 

 polymorphous species, the forms owing their very considerable 

 differences to variations in the environmental conditions under 

 which they may be found growing. It is our experience that all 

 of the jointed Corallinaeea? are very susceptible to such condi- 

 tions as greater or less depth of submergence, varying light, 

 temperature, impurity or purity of water, especially the admix- 

 ture, continuous or otherwise, of fresh water, exposure to air and 

 sun when emergent, etc. The grinding of sand in the currents 

 flowing over them or the mutilations by animals, produce vari- 

 ations in habit and the form of the individual joints, sufficient to 

 disturb the typical aspect of the species. We have preferred to 

 use the oldest specific name for the group of forms, although it is, 

 perhaps, the least descriptive. We do not understand the reasons 

 for referring some of the forms to the genus Cheilosporum, as 



