325 [VerriU. 



the Gulf Stream flowed across the isthmus into the Pacific, Avithin 

 comparatively recent geological times. Indeed the Palaeontology of 

 the eastern coast of the United States, in connection with that of 

 California and Western America, so far as it is known, would rather 

 show, as do the living faunae, that there has been no connection, or at 

 least none sufficient to materially change the course of the Gulf 

 Stream, since the commencement of the Tertiary Period. The 

 fossils of the Eocene and Miocene deposits of the Southern States 

 are, to a great extent, similar in their distribution to the living 

 forms that have taken their places, and in numerous instances are 

 more nearly allied to the corresponding living faunas than the faunee 

 of the two sides of the Isthmus are to one another. 



Even in the Glacial, or Drift Period, the arrangement of the differ- 

 ent marine faunae along our coast was essentially the same as at pres- 

 ent. The Arctic faunae having descended only a few hundred miles 

 farther south, to the coast of New England, while south of Cape 

 Cod, the greater part of the fossils of that period are now living in 

 adjacent waters. There are also facts that go to show that at that 

 time the Carolina coast was even warmer than at present. One of 

 the principal changes that appears to have taken place since the 

 Tertiary Period, has perhaps been caused by the permanency and 

 continued uniform action of the Gulf Stream itself: namely, — the 

 fauna of the coast of Texas, and the other States bordering on the 

 Gulf of Mexico, which is so similar to that of Georgia and the Carolinas 

 that we may suppose that at one time they were directly connected, 

 and have become gradually separated by the southern extension of 

 the Peninsula of Florida, in consequence of the gradual introduction 

 of West Indian species of corals, which have formed reefs, and thus 

 continually increased the separation of the two more temperate 

 regions by an extending cape, essentially West Indian in its faunal 

 characters. 



This long continued gi'owth of the reefs has required an equally 

 prolonged and uniform flow of the Gulf Stream, the direction of 

 which has, perhaps, been somewhat altered in consequence of the ex- 

 tension of the reefs. The existence of the extensive coral reefs of 

 Bermuda is also wholly dependent upon the prolonged and uniform 

 flow of the Gulf Stream with nearly its present direction and force, 

 for those reefs are nearly identical Avith those of the West Indies and 

 Florida in structure, and in the species of corals that form them, 

 and are so far north that they could not have begun to exist until the 

 present course of the Gulf Stream had been established, and the 

 floating coral germs had been carried there from the West Indies or 

 Florida. 



Therefore, had the Gulf Stream ever flowed across the Isthmus 



