Distribution of the Laminar iacem. 361 



The northern Atlantic and Arctic Districts then are nearly related, 

 the districts of Spitzbergen, western Europe and northern Europe 

 being the most alike, the district of northern Asia having something 

 in common with the northern Pacific, and New England and Baffin 

 Bay having also a prominent genus in common with the northern 

 Pacific. 



In the northern Pacific we have separated four districts, each of 

 which has its peculiar interest. Two of these are on the western 

 coast of North America and the other two are on the eastern coast 

 of Asia. The species of all of these are in considerable confusion 

 at present, but enough perhaps is certain to afford a fair basis for 

 comparison. 



The district of Alaska is credited in the above table with 30 

 species and the district of California with 15. They have however 

 but 3 species in common. This number may be so small because 

 of our imperfect knowledge, but there can be little doubt that there 

 is a great dissimilarity in the kelp-floras of the two districts. While 

 Alaska possesses 14 species of the Laminariese and 10 Alariese, Cali- 

 fornia has but 3 of the former and but 2 of the latter, 1 species of 

 which is the peculiar Pterygophora Calif ornica, Rupr. Alaska also 

 possesses 5 species of Agareae while California has but 1. On the 

 other hand Alaska has no representative of the Lessonese while Cali- 

 fornia possesses 5, and no members of the Ecklonege against 2 be- 

 longing to California. Alaska possesses members of the Laminariese, 

 Agaiese, Macrocysteae, and Alarieae while California has representa- 

 tives of all the 8 subtribes along its coast. Of the 15 species 

 credited to California, 10 are peculiar to it. Of the remaining 5, 

 3 are found also in Alaska, 1 also in Japan, 1 also on the shores of 

 Kamtschatka, while 3 are species also found in the southern hemis- 

 phere. The only one found also in the northern Atlantic or Arctic 

 Oceans is Alaria esculenta and it is doubtful whether this species as 

 understood by Kjellman is really present in Californian waters. 



The case is much different with the district of Alaska. It has 6 

 species in common with Spitzbergen and 9 with Baffin Bay, while 

 the only species it has in common with the southern Pacific is 

 Macrocystis pyrifera^ Ag. 



On the opposite side of the Pacific Ocean, in the districts of 

 eastern Asia we find a somewhat similar state of tliinos. Here we 

 have a northern district, viz : the district including the Sea of 

 Ochotsk and Kamtschatka, and a southern district including the 

 larger islands which belong to Japan. The Ochotsk district has 



