THE PELAGIC FAUNA AND FLORA. 209 



long trains or patches of a dirty yellow color. Dr. Farlow has 

 identified as the same alga the pelagic plant found on one 

 occasion north of Cape Hatteras, tinting the surface of the sea 

 a dirty yellow for an area of about a quarter of a mile in length 



133. — Tricliodesniium Fig. 134. — Coccosphere. Fig. 135. — Rhabdosphere. 



erythrfeum. f. Afio. (Chall.) ^^. (Chall.) 



hy a hundred yards in width. This pelagic alga has been aptly 

 described as resembling minute sheaves and bundles of chopped 

 hay. Coccospheres (Fig. 134) and rhabdospheres (Fig. 135) 

 are calcareous pelagic surface organisms, of which the tests 

 and fragments, coccoliths and rhabdoliths, occur in numbers in 

 globigerina ooze. They have been studied by the naturalists of 

 the " Challenger," and Thomson regards them as calcareous 

 algae of a peculiar form. They are found in abundance in the 

 stomachs of Salpse. 



In addition to these smaller algse, which are indeed the true 

 inhabitants of the surface, and flourish equally well in all parts 

 of the ocean, — in the central parts of the Gulf of Mexico, along 

 the Atlantic coast of the United States, or on the west coast of 

 South America, — we find some of the higher algae, but these 

 are confined to very much more limited areas. Sir Joseph 

 Hooker has described the giant kelp in the floating condition 

 in which it rangfes over a wide extent of the Southern Ocean. 

 A similar species of kelp occurs in the Gulf of Georgia, where 

 it serves as a refuge to a host of marine animals, which are 

 sheltered within the comparatively quiet area occupied by it. 

 Both in the Atlantic and Pacific, large tracts are covered by 

 a species of Sargassum (Fig. 136), which in the Atlantic has 

 given its name to the area known as the Sargasso Sea.^ 



1 The Sargasso Seals an immense body with a thickness of 300 fathoms, the sur- 

 of warm water of 1,000 miles in diameter, face temperature of 22° C, diminishing 



