158 On an Isothermal Oceanic Chart, illustrating 
A ninth region—called the Polar—may be added, if it should 
be found that the distribution of species living in the Frigid zone 
requires it. There are organisms that occur in the ice and snow 
itself of the polar regions; but these should be classed with the 
animals of the continents ; and the continental isotherms or iso- 
erymes, rather than the oceanic, are required for elucidating their 
distribution. 
It seems necessary to state here the authorities for some of the 
the Little and Great Bahamas. To the eastward, near the 
African Coast, it has a flexure northward, arising from the hot 
waters along the coast of Guinea, which reach in a slight current 
upward towards the Cape Verde Islands. ‘The line passes to the 
south of these islands, at which group, Fitzroy, in January of 
1852, found the sea temperatures 71° and 72° F. 
Lsocryme of 68° F.—Cape Canaveral, in latitude 27° 30/, just 
north of the limit of coral reefs on the east coast of Florida, is the 
western termination of the line of 68°. The Gulf Stream oc- 
casions a bend in this line to 36° north, and the polar current, east 
of it, throws it southward again as far as 29° north. Westw 
it inclines much to the south, and terminates just south of Cape 
Verde, the eastern cape of Africa. Sabine found a temperature 
of 64° to 65° F’. off Goree, below Cape Verde, January, 1822; 
and on February 9, 1822, he obtained 663° near the Bissao 
shoals. ese temperatures of the cold season contrast strikingly 
with those of the warm season. Even in May (1831), Beechey 
had a temperature of 86° off the mouth of Rio Grande, between 
the parallels of 11° and 12° north. 
socryme of 62° E'.—'This isocryme leaves the American coast 
at Cape Hatteras, in latitude 354° north, where a bend in the out- 
line of the continent prevents the southward extension of the 
polar currents close along the shores. It passes near Madeira, and 
bends southward reaching Africa nearly in the latitude of the 
Isocrymes of 56° and 50° F.—Cape H atteras, for a like reason, 
is the limit of the isocrymes of 56° and 50° as well as of 62° 
