360 W. A. Setchell — Classification and Geographical 



are at all ''warm." So thj^t the distribution of the kelps is limited 

 toward the poles by the presence of ice for too long a portion of 

 the year, and in the directions away from the poles by the limits of 

 the various colder currents. The tropical currents and waters are 

 interesting as acting as barriers against farther distribution in cer- 

 tain waters. 



In studying the table of distribution just given, we notice certain 

 features which are of interest and imiDortance. It will be best, per- 

 haps, to consider these general features of distribution, first by pro- 

 vinces, and then by tribes and subtribes. 



The district of northern Asia (or of the Siberian Sea)' possesses 

 four species of Laminaria and three of Alaria. Of the latter two 

 are peculiar to this district and one is found also on the coast of 

 Alaska. Of the four Laniinarice, one is found also in Alaska, and 

 the other three are found in the northern Pacific (Alaska or Sea of 

 Ochotsk) and in the Arctic Sea, either in northern Europe or more 

 northern, in Spitzbergen, or Baflin Bay. So that the kelp-flora of 

 this district is related both to that of the north Atlantic and Euro- 

 pean Arctic as well as to the northern Pacific. 



The districts of northern Europe, Spitzbergen, and western Europe 

 are very much alike in general features. Their kelp-flora is made 

 up of the members of the Laminarieie and Alariete alone. Even 

 Agarum, so abundant in Baflin Bay and Xew England, is not pres- 

 ent. Altogether they possess twenty-one species, of which four 

 are common to all three, while nine species are common to northern 

 Europe and Spitzbergen, on account of the colder waters of these 

 districts. There are also eight species common to both northern 

 and western Europe. In fact the differences between these districts 

 is mostly one of colder and warmer water species. 



When we turn to the districts of Baflin Bay and Xew England, 

 we find that not only are the Laminaries and the Alarie^e repre- 

 sented, but also the subtribe Agarese. They have eight species in 

 common. The four species common in northern Europe, western 

 Europe and Spuzbergen are also found in these two districts. They 

 have six species in common with Spitzbergen and northern Europe, 

 while New England has seven species in common with both northern 

 and western Europe. 



The possession of Agaruni Turneri suggests a comparison with 

 the district of Alaska, with which New England has seven species 

 in common and Baflin Bay nine. 



' Cf. Kjellman, Arctic Algae, p. 5. 



