64 STEPPES AM) DESERTS. 



Corvo, one of the Azores ; while the lesser and western- 

 most bank, of a roundish form, is situated between the 

 Bermudas and the Bahamas, (lat. 25-31, long. 66-74.) 

 The longer axis of the small bank which is crossed by 

 ships going from Baxo de Plata (Caye d' Argent, Silver 

 Cay) on the north of St. Domingo, to the Bermudas, 

 appears to have a N. 60 E. direction. A transverse band 

 of Pucus natans, running in an East and West direction 

 between the parallels of 25 and 30, connects the greater and 

 lesser banks. I have had the 'gratification of seeing these in- 

 ferences approved by my honoured friend Major Eennell, and 

 adopted by him in his great work on Currents, where he has 

 further supported and confirmed them by many new and addi- 

 tional observations. (Compare Humboldt, Relation Histo- 

 rique, torn. i. p. 202, and Examen critique, torn. iii. p. 68-99, 

 with RennelTs Investigation of the Currents of the Atlantic 

 Ocean, 1832, p. 184.) The two groups of sea-weed, 

 included together with the transverse connecting band 

 under the old general name of the Sargasso Sea, occupy 

 altogether a space exceeding six or seven times the area of 

 Germany. 



Thus it is the vegetation of the ocean which offers the 

 most remarkable example of an assemblage of "social 

 plants" of a single species. On terra firma, the savannahs 

 or prairies, or grassy plains of America, the heaths (ericeta), 

 and the forests of the North of Europe and Asia, consisting 

 of coniferous trees, birches, and willows, offer a less degree 

 of uniformity than do those thalassophytes. Our heaths 

 show, in the north, in addition to the prevailing Calluna 



