GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA. 1463 



found the mean temperature of the sea for December, 1827, 74-63° 

 F.; for January, 73-69° F.; for February, 72-40° F. The line of 74° 

 F. commences therefore a degree or two south of San Bias. In the 

 winter of 1827 on January 16 to 18, the temperature of 74*3° to 

 74-6° F. was found by Beechey, in 16° 4' to 16° 15' north, 132° 

 40' to 135° west; and farther west, in the same latitude, longitude 

 141° 58' west, the temperature was 74-83° F. West of the Sandwich 

 Islands, near the parallel of 20° north, the temperature rises five degrees 

 in passing from the meridian of 165° west to 150° east, and the iso- 

 cryme of 74° F., consequently rises somewhat to the north, over this 

 part of the ocean. Between the meridians of 130° and 140° east, the 

 temperature of the sea is quite uniform, indicating no northward flexure ; 

 and west of 130° east, nearing China, there is a rapid decrease of tem- 

 perature, bending the line far south. Vaillant, of the Bonite, found 

 the sea off Cochin China, in latitude 12° 16' north, 109° 28' east, 

 to have the temperature 74*12° F.; and even at Singapore, almost 

 under the equator, the temperature on February 17 to 21, was 77-54° 

 to 79-34° F. The isocryme of 74° F. terminates therefore upon the 

 southeastern coast of Cochin China. 



Isocryme of 68°.— Off the Gulf of California, in 25° north, 117° west, 

 Beechey obtained for the temperature of the sea, on December 13, 

 65° F.; on December 15, in 23° 28' north (same latitude with the 

 extremity of the peninsula of California), 115° west, a temperature of 

 69-41° F. The line of 68° will pass from the extremity of this penin- 

 sula, the temperature of the coast below, as it is shut off mostly from 

 the more northern and colder waters, being much warmer. The tem- 

 perature 69-41° in the middle of December, is probably two and a 

 half degrees above the cold of the coldest month, judging from the 

 relative temperatures of the latter half of December and the month of 

 February at San Bias. Leaving California, the isocryme of 68° will 

 therefore bend a little southerly to 22$°, in longitude 115° west. In 

 23° 56' north, 128° 33' west, Beechey, on January 11, found the 

 temperature of the sea 67-83° F. The line of 68° passes north of the 

 Sandwich Islands. The mean temperature of the sea at Oahu in 

 February, 1827, was 69-69° F. 



Near China, this isocryme is bent far south. At Macao, in winter, 

 Vaillant found the sea-temperature, on January 4, 59° F.- on January 

 5 to 10, 52-7° to 50° F.; January 11, 12, 49*87° to 48-74° F.; January 

 13 to 16, 50-9° to 52-16° F.; and at Touranne in Cochin China, on 

 February 6 to 24, the sea-temperature was 68° to 68 h° F.; in 16° 22' 



