Distribution of the Laminariacem. 373 



when northern Europe was surrounded with a sea filled with ice 

 stretching down to the present northern coast of France. It is not 

 at all improbable that the flora of this sea may have been similar to 

 that of the present Arctic Sea. When the glacial formation dimin- 

 ished in the south, southern plants immigrated in the sea as well as 

 on the land, dislodging the main mass of the glacial ones. However, 

 some of these being able to hold out the struggle against the new- 

 comers, maintained themselves in their original home and have done 

 so ever since." Kjellman has still farther discussed this matter in 

 connection with a number of species of Arctic algae. 



Chorda filuni (L), Stackh. is an interesting form, taken in this 

 connection. It is abundant on the western coast of Europe and on the 

 northeastern coast of North America and occurs in the intermediate 

 regions at Spitzbergen and Iceland where it is rather scarce, and on 

 all the coast of Greenland where it is more abundant. It is found 

 also in Japan and Alaska. It may possibly have migrated thence 

 through the Siberian Sea or even through the American Arctic Sea, 

 but we have no trace of it in these seas and the currents are such as 

 not to favor it. It seems probable that it may have been a common 

 form in the polar sea when it was more open than it is now and 

 became, consequently, a member of each of the four colonies driven 

 southward by glaciation. Yery similar is the case of Saccorhiza 

 dermatodea^ DelaPyl. and perhaps also those of Lmninaria digi- 

 tata (L.), Lam'x., L. stenophylla (Ilarv.), J. Ag., L. nigripes, J. 

 Ag., L. fissilis, J. Ag., Alaria esoidenta (L), Grev., and A. Pylaii 

 (DelaPyl.), J. Ag. 



A couple of interesting problems are presented b}^ the distribu- 

 tion of Jjarninaria longicritris^ DelaPjd. and Agarum Tumeric 

 P.&R. Neither of these species are represented on the shores of 

 Europe or of northern Asia but they both occur on the northeastern 

 and northwestern coasts of North America. It is not easy to 

 account for the non-existence of these forms on the coast of Europe. 



Ij. lo7igicruris^ DelaPyl. is certainly carried to the coasts of 

 western Europe by the Gulf Stream but arrives there in a battered 

 and macerated condition and fails to effect a foothold.^ Agartmi 

 Turneri, Grev. is not known at all on European shores. It may 

 have been brought by the easterly currents through the American 

 Arctic Sea from Alaska, where it exists in several varieties and in 

 abundance, to Greenland and New England, or it may possibly have 

 been a circunipolar species at one time and have become extinct on 



> Cf. Aresch. Obs. Phyc, Pt. 4, p 8. 



