344 University of California Publications. [botany 



waters. He also says that it is a comparatively common plant in 

 Pit get Sound, while on the central Californian coast it is rarely 

 found . We have not seen any specimens referable to the genuine 

 A. Plumula from any portion of the western coast of North 

 America. 



Antithamnion boreale f; typica Kjellman. 



On rocks and wood in the litoral zone. Port Clarence and 

 St. Lawrence Island, Alaska, Kjellman (1901, p. 33); Cape Den- 

 bigh, Norton Sound, Alaska, R. C. McGregor, No. 5661! ; Friday 

 Harbor, San Juan Island, Wash., X.L.G., No. 490! 



This form runs into the next and it is often difficult to 

 determine to which form a given plant is to be referred. 



Antithamnion boreale f. corallina Kjellman. 



On rocks in the middle and lower litoral zones. Besboro 

 Island, Norton Sound, Alaska, B. C. McGregor, No. 5662! ; 

 Cormorant Rocks, U yak Bay, Kadiak Island, Alaska. W.A.S. and 

 A.A.L., No. 5135! ; Sitka and Wrangell, Alaska, Saunders (1901, 

 p. 34!). under Antithamnion boreale). 



Saunders's specimens are placed here because he says that they 

 are very close to this form. All the species of Antithamnion seem 

 to be connected by intermediate forms from the simplest forms 

 of .1. boreale up to the most complex forms of A. Pylaiscei or ^4. 

 subulatum. We may well believe with Kjellman (1883, p. 181) 

 that "the genus Antithamnion is a young genus whose species 

 arc in course of development, no marked differentiation being as 

 yet established and the transitional forms not having disappeared." 



Platythamnion heteromorphum f. typicum Setchell and 

 Gardner comb, now 



( last ashore. West coast of Whidbey Island, Wash., K.L.G., 

 Xos. 164!, 408!; Friday Harbor, San Juan Island, Wash.. 

 Tilden, No. 310!, under Callithamnion subulatum. 



The plants referred here seem to agree well with the descrip- 

 tions of J. G. Agardh (1876, p. 23, and 1892, pp. 22, 23.) The 

 pinnules have branehlets distichous and ou both sides below, but 

 secund and on the upper side, above. 



