Section II.— BOTANICAL. 



General Characteristics of the Algal Vegetation of Buzzards Bay and Vineyard 

 Sound in the Vicinity of Woods Hole. 



By Bradley Moore Davis. 



Chapter I.— INTRODUCTION. 



Ever since the publication of Harvey's "Nereis Boreali-Americana," in 1852, 1857, 

 it has been recognized that the marine algae of the Atlantic coast of North America 

 were separated by Cape Cod into two floras. The distinction was discussed in detail in 

 Farlow's report "The Marine Algae of New England," 1881, and in his earlier "List of 

 the Sea-weeds or Marine Algae of the South Coast of New England," 1873. The work 

 of later algologists has only served to emphasize the fundamental differences between 

 the two marine floras, and the results of this survey add further evidence in support of 

 this general conclusion. 



Similar conclusions have been reached by zoologists respecting the distribution of 

 marine animals north and south of Cape Cod. The fauna from the cape northward to 

 Labrador is regarded as essentially a continuous one, with no changes that are com- 

 parable to those which appear southward. Two faunas separated by Cape Cod have 

 thus been distinguished, and there seems to be a difference between these similar to that 

 between the two marine floras. The most important reasons for the difference between 

 the faunas and floras north and south of Cape Cod are undoubtedly the same. 



The marine algae north of Cape Cod, as pointed out by Farlow (1881), are in general 

 a part and continuation of the flora of Greenland and Newfoundland. Many of the 

 most characteristic species of the flora, as judged quantitatively, are identical with those 

 of the Scandinavian coast, and it seems clear that the algae of the west and east side of 

 the north Atlantic are a part of a general Atlantic boreal flora. 



The reason for the boreal character of the algal flora north of Cape Cod is undoubt- 

 edly the low range of temperature which prevails even through the warmer months of 

 the year. The coast is bathed by a belt of cold water that lies between the coast and 

 the Gulf Stream, this belt being from 200 to 250 miles broad off a large part of the New 

 England coast, although the Gulf Stream is only about 80 miles from Marthas Vineyard 

 and Nantucket. The temperature of these waters, except in sheltered situations, only 

 reaches 6o° F. or slightly above for a few weeks in midsummer, and for the greater part 

 of the year is below 50 , and remains below 40 throughout the winter. The explanation 

 of this condition involves a number of factors, which are discussed in section 1, chapter 

 n, pages 35 and 51, to which the reader is referred for details. The most important 

 point for present consideration is the undisputed fact of the presence of a belt of rela- 

 tively cold water north of Cape Cod, lying between the Gulf Stream and the New 

 England shores, which directly influences the algal flora. 



The marine algae south of Cape Cod may be grouped into what Harvey (1852, p. 26) 

 calls the flora of Long Island Sound, extending from Cape Cod to New Jersey. It includes 



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