210 J. D. Dana on an Isothermal Oceanic Chart, 



extends to Rio Janeiro, in 24° south. The Warm Temperate 

 region, if at all found north of Cape Blanco, 4f ° S., has a 

 breadth of less than a degree, while that of the Atlantic ex- 

 tends to Rio Grande, in 33° south. The next, or Temperate 

 Region, has a longer range on the South American coast, 

 extending to Copiapo, in 27a-° south, and the Atlantic region 

 corresponding goes to Maldonado, in 35° south. The Cold 

 Temperate regions of the two oceans cover nearly the same 

 latitudes. 



On the North American coast at Cape Hatteras, the three 

 isocrymes 62°, 56°, and 50° F., leave the coast together ; and 

 in the Pacific, on the South American coast, there is a similar 

 node in the system of isocrymes, the three, 74°, 68°, and 62°, 

 proceeding nearly together from the vicinity of Cape Blanco. 



Viewing these regions through the two oceans, instead of 

 along the coasts, other peculiarities no less remarkable are 

 brought out. The average breadth of the South Torrid re- 

 gion in the Pacific, is more than twice as great as that of 

 the same in the Atlantic ; and the most southern limit of 

 the latter is five degrees short of the limit of the former in 

 mid-ocean. So also the Subtorrid region, at its greatest 

 elongation southward in the Atlantic, hardly extends beyond 

 the mean course of the line of 68° F. in the Pacific, and the 

 average breadth of the former is but two-thirds that of the 

 latter. The same is true to an almost equal extent of the 

 Warm Temperate and Temperate Regions. 



The breadth of the Torrid Region of the Pacific to the 

 eastward, where narrowest, is about six degrees ; and to the 

 westward, between its extreme limits, forty-nine degrees. 

 The Torrid zone or Coral-reef Seas, in the same ocean, has 

 a breadth near America of about eighteen degrees, and near 

 Australia and Asia, of sixty-six degrees. 



New Zealand lies within the Subtemperate and Cold Tem- 

 perate regions, excepting its southern portion, which appears 

 to pertain, like Fuegia, to the Subfrigid. Van Diemen's 

 Land, exclusive of its northern shores, is within the Cold 

 Temperate. 



Other particulars respecting the temperature regions 

 through the Pacific will be gathered from the chart. 



