Cue Mes 
Pees 
130 On the Temperature limiting the Distribution of Corals. 
Arr. XV.—On the Temperature limiting the Distribution of 
Corals; by James D. Dana, Geologist of the United States 
Exploring Expedition. 
[Read before the Association of American Geologists and Naturalists, at Albany, 
April 29, 1843.] 
I wave before stated to the Association, that the temperature 
limiting the distribution of corals in the ocean is not far from 66° F’. 
On ascertaining the influence of temperature on the erowth of 
corals, I was at once enabled to explain the singular fact that no 
coral occurs at the Gallapagos although under the equator, while 
growing reefs have formed the Bermudas in latitude 33°, four or 
five degrees beyond the usual coral limits. In justice to myself I 
may state here, that this explanation, which was published some 
two years since by another, was originally derived from my man- 
uscripts, which were laid open most confidingly for his perusal, 
while at the Sandwich Islands in 1840.* The anomalies which 
the Gallapagos and Bermudas seemed to present, were dwelt upon 
at some length in the manuscript, and attributed in the datter 
case to the influence of the warm waters of the Gulf Stream; in 
the former to the southern current up the South American coast, 
whose cold waters reduce the ocean temperature about the Gal- 
lapagos to 60° F. during some seasons, although twenty degrees 
to the west, the waters stand at 84° F. Hvtratropical currents, 
like that which flows by the Gallapagos, are found on the west- 
ern coasts of both continents, both north and south of the equa- 
tor, and intratropical currents are as distinctly traceable on the 
eastern coasts.+ In consequence of these currents, the coral zone 
is contracted on the western coasts and expanded on the eastern; 
it is reduced to a width of sixteen degrees on the western coast 
of America, and of but twelve degrees on the east coast of Amer- 
ica; while in mid-ocean it is at least fifty-six degrees wide, and 
about sixty-four degrees on the east coast of Asia and New Hol- 
* The publication here alluded to we understand refers to an article by 
r. J. P. Couthouy, which appeared last year in the Boston Journal of Natural 
History. —Eps. 
t The existence of these great oceanic currents was first pointed out to me by 
our distinguished meteorologist, Mr. Wm. C. Redfield, who kindly furnished me 
with charts of the same before the sailing of the Expedition. 
