1466 



CRUSTACEA. 



south, 13G 51' west. These observations give a wide sweep to the 

 cold waters of the colder seasons, and throw the isocrymes of 74 and 

 68 F., far west of the Gallapagos. Captain Wilkes, in passing directly 

 west from Callao, found a temperature of 68 F., in longitude 85 

 west; 70 F., in 95 west; and 74 F., in 102 to 108 west. These 

 and other observations lead to the positions of the isocrymes of 74, 

 68, and 62, given on the Chart. The line of 74 passes close by 

 Tahiti and Tongatabu, and crossing New Caledonia, reaches Australia 

 in latitude 25 S. 



In mid-ocean there is a bend in all the southern isocrymes.* 



* The following observations by Mr. W. C. Cunningham (in connexion with those of 

 other navigators), establish the fact of this flexure; they were sent by him to the 

 author, in a letter, dated Talcahuano, Chili. 



1. FROM THE HAKBOUR OF APIA, ISLAND OF TJPOLU, TO TAHITI. 



t Mean temperature. 



