352 W. A. Setchell^ Classification and Geographical 



15. Echlonia^ Hornem.-^The main portion of the blade persisting, 



destitute of ciyptostomata. 



16. Elsenia, Aresch. — The main portion of the blade disappearing 



early destitute of cryptostomata. Stipe bifurcate, above in all 

 except A'ery young specimens. 

 Subtribe 2. Esrregieae. — Sporophylls situated upon both blade and 

 stipe. 



17. Egregia, Aresch. — Frond irregularly branched. 



Subtribe 3. Alarieae. — Sporophylls situated upon the stipe alone. 



18. PterygopTiora^ Rupr. — Terminal blade provided with an indefi- 

 nite midrib but destitute of cryptostomata. Sporophylls of 

 indefinite growth. 



19. Alaria, Grev. — Terminal blade provided with a distinct midrib 



and with cryptostomata. Sporophylls of definite growth. 



Geographical Distribution of the LaminariacecB. 



As far as the writer is aware, nothing has been written on this 

 subject as a whole. Hooker^ speaks at length, of the distribution of 

 Macrocystis. Kjellmann in his "Arctic Algae" treats of the dis- 

 tribution of the northern kelps very carefully, in connection with 

 the other algae of the Arctic Sea. But apart from these the refer- 

 ences are scattered and the main features are left unemphasized. 

 It is the desire of the writer to bring these more general facts of 

 distribution together in one place. 



The kelps inhabit the colder waters of the globe, delighting in the 

 marine waters of the frigid and colder temperate zones, and absent 

 or all but absent from the warmer temperate and tropical oceans. 

 In selecting, then, our regions to be considered, we can leave out 

 practically all the middle portions of both the larger oceans as well 

 as all the Indian Ocean, and confine our attention to the Arctic 

 Ocean, the northern portions of the Atlantic and Pacific, and to the 

 southern portions of the same oceans together with the Antarctic 

 Ocean. 



The Northern Atlantic and Arctic Oceans. — We may distinguish 

 under this head six different districts^ whose kelp-floras differ sufli- 

 ciently to receive, each its special mention. The districts are those 

 of northern Asia, northern Europe, western Europe, Spitzbergen, 

 Baftin Bay, and New England. 



' Flora Antarctica, Pt. 2, pp. 461-465. 



^ These are merely geographical districts selected for convenience in dividing up the 

 •coast and not true provinces as regards similarity of inhabitants. 



