the Geographical Distribution of Marine Species. 161 
to 31, 1832, found the sea-temperature at Montevideo 56° to 58° 
d in August, 57° to 544° F. These observations would 
ie 
5 
temperature 56 FE. was also observed in 35° south, 53° west, and 
t 36° south, 56° 36’ west. But on July 10 and 13, 1833, at 
Montevideo, the sea-temperature was 464° to 474°, a degree of 
cold which, although only occasional, throws the line of 56° F. 
to the north of this place. The temperature near the land is 
several degrees of Fahrenheit lower than at sea three to eight de- 
grees distant. East of the mouth of the La Plata, near longitude 
30° west, Beechey, in July, 1828, found the temperature of the 
sea 61'86° F. So in April 23 to 29, Vaillant obtained the tem- 
perature 59-5° to 61°25° F. at Montevideo, while in 35° 5’ south, 
49° 23’ west, on April 14, it was 66-2° F., and farther south, in 
37° 42’ south, 53° 28’ west, April 30, it was 64-4° F.; and in 
39° 19’ south, 54° 32’ west, on May 1, it was 573° F.; buta 
little to the westward, on May 2, in 40° 30’ south, 56° 54’ west, 
the temperature was 48° F., an abrupt transition to the colder 
shore waters. Beechey, in 39° 31’ south, 45° 13’ west, on Aug- 
ust 28 (last of winter), found the temperature 57-25° F., and on 
the 29th, in 40° 27’ south, 45° 46’ west, it was 54:20° ; while on 
the next day, in 42° 27’ south, 45° 11’ west, the temperature fell 
to 47-839 F, These and other observations serve to fix the posi- 
tion of the isocryme of 56°F. It approaches the African coast, 
in 32° south, but bends upward, owing to cold waters near the 
land. On August 20, Vaillant, in 33° 43’ south, 15° 51’ east, 
found the temperature 56° F'.; while on the 22d, in the same 
latitude, and 14° 51’ east (or one degree farther to the westward), 
the temperature was 57°74° F., being nearly two degrees warmer. 
At Cape Town, in June (latitude 34°), Fitzroy found 55° to 61° 
F., while on August 16, farther south, in 35° 4’ south, and 15° 
AQ’ west, one hundred and fifty miles from the Cape, Vaillant 
found the temperature 59-26° EF. The high temperature of the 
last is due to the warm waters that come from the Indian Ocean, 
and which afford 61° to 64° F. in August, off the south extremity 
of Africa, west of the meridian of Cape Town. 
he isocryme of 50° F. leaves the American coast just south 
of the La Plata; after bending southwardly to the parallel of 419, 
it passes east nearly parallel with the line of 56°F. It does not 
reach the African coast. ‘ 
Tsocrymes of 44° and 35° F.—Fitzroy in August (the last win- 
ter month) of 1833, found the sea-temperature at Rio Negro 
(latitude 41° south) 484° to 50°F. But during the voyage from 
the La Plata to Rio Negro, a few days before, a temperature of 
443° to 46° was met with; this was in the same month in 
which the low temperature mentioned above was found at 
Montevideo. he bend in the course north of the entrance to 
Srconp Serizs, Vol. XVI, No. 47.—Sept., 1853. 21 
