Vol. n SetcJiell-Gardner. — Alga' of Northive stern America. 287 



either solved, or at least, have not left in such a condition as 

 to confuse others. We have preferred here, as in the fore- 

 going groups, to deal with what seem to be polymorphous 

 species in many cases, and have adopted the method of 

 naming forms to give detiniteness to our ideas of the amplitude 

 of variation. Our studies on the Calif ornian Coast have helped 

 us much in realizing the extreme variation which a specie? of 

 algae may undergo under circumstances of varying environmental 

 conditions and still adhere to the general type. We have fol- 

 lowed in general arrangement and largely in the selection of the 

 generic names and generic distinctions, the work of Schmitz and 

 his collaborators, Haupttleisch and Falkenberg (1S9G-1897) in 

 Engler and Prantl. In some cases, we have departed and have 

 followed J. G. Agardh in his later arrangements of the genera 

 formerly grouped under Delesseria and Callithamnion, and for 

 good reason as it has appeared to us. We have also found much 

 help on many groups from Kjellman's critical notes in the Algae 

 of the Arctic Sea (1888) . For unravelling the difficulties in some 

 genera, Ruin-echt (1851) has been indispensable and Kuetzing's 

 Tabula^ Phycologicee have assisted greatly. In this group, partic- 

 ularly, which has been less thoroughly studied, it has been 

 necessary to examine all the literature available in almost every 

 case. We have derived very considerable information from 

 Yendo's papers on Corallinge Verae (1902 and 1902a), although 

 we cannot agree with him in the closeness of his specific distinc- 

 tions. 



We are indel)ted to j\[. Foslie of Trondheim, Norway, for the 

 account of the crustaceous Corallinaceae, and to Mr. F. S. Collins, 

 and through him to Professor W. G. Farlow, for lieli) in many 

 cases of troublesome synonymy. To Mr. H. T. A. Hus, we are 

 desirous of expressing our thanks for examining all of the mate- 

 rial of the genus Porphyra and for the masterly way in which he 

 has unravelled the difficulties of specific distinction in that genus. 



As regards comparative distribution of the species of this 

 large group, we are, as yet, hardly in a position to make any 

 very general or explicit statements. A very considerable number 

 of the species found in the North Temperate Region of the Pacific 

 Coast of North America are continued into Puget Sound, and 



