370 W. A. SetcheU — Classification and Geographical 



Macrocystis in the eastern hemisphere, are considerably to the south 

 of it. 



The isothere of 20° seems to limit tlie species of the three sub- 

 tribes named above more or less sharply. This line touches the 

 western coast of Europe just above Gibraltar and the coast of 

 eastern Northern America in the neighborhood of Cape Cod. The 

 colder species of both coasts reach their limits somewhat to the 

 north of these points, probably at about 18^ of surface temperature 

 and either go down into deeper waters or are found only at exposed 

 points to the southward. Such is the case with Af/arwn Turnerh 

 P.&R. on the Massachusetts coast' and Laminaria digitata (Turn.)' 

 Lam'x, south of Cape Cod." 



We find the same state of thing^s in the northern Pacific. The 

 characteristic Laminarieoe, Agare^e, and Alariese stop at about Puget 

 Sound which is the terminus of the isothere of 15°, but Costaria 

 Tumeric Grev. and Alaria esculenta (L.), Grev. (as we still call the 

 Californian form or forms) continue to Monterey nearly to the 20° 

 line, although they are found only at "exposed points." The typi- 

 cal Laminarice of California are L. Andersonii^ Farlow, X. Far- 

 lowii, Setchell, and L. Sinclairii (Harv.\ Farlow, whose range 

 toward the north stops, as far as we know, below the isothere of 

 15°. An interesting case is that of Pterygophora Calif ornica^ Rupr. 

 which is reported by Dr. C. L. Anderson, as growing at Monterey 

 all the year round but is reported by Mr. Daniel Cleveland as occur- 

 ring at San Diego only from February until May and in deep water.^ 



On the coast of Asia the isothere of 20° reaches the coast of Yezo 

 and there stops the southward range of the species characteristic of 

 Behring Sea. On the eastern coast of Nippon, however, are found 

 the characteristic species of Laminaria Japonica^ Aresch., L. 

 Peterseniana, Kjellm., X. radicosa, Kjellm., and Alaria crassifolia^ 

 Kjellm. 



Those members of the Laminariacene which partake of the Eck' 

 lonia-ly^e^ of structure seem to prefer warmer waters than the 

 majority of the sj^ecies of the three subtribes mentioned above. 

 Egregia is found only on the coast of California between the 

 isotheres of 15° and 20°, mostly in the neighborhood of the latter 

 and to the south of it. Eisenia has very nearly the same range. 

 The species of Ecklonia are found on the south and west coasts of 

 Australia between the isotheres of 20° and 30°, at the Cape of Good 



1 Cf. Farlow, New Entrland Algte, p. 96. ' Cf. Farlow, loc. cit., pp. 4 and 94. 



^ Cf. Hervey, Sea Mosses, p. 89, 18SI. 



