illustrating the Distribution of Marine Animals. 217 



socryme 



of 80° F., 



Parallel of 6 



■>"> 



74 „ . 



20 



55 



68 ,, 



27 



55 



62 „ 



32 



55 



56 „ 



37 



55 



50 „ 



42 



55 



44 „ 



47 



55 



35 „ 



56 



Using these results as a key for comparison, we at once 

 perceive the great influence of the oceanic movements on 

 climate, and on the geographical distribution of marine 

 life. 



The polar or extra- tropical current of the Southern At- 

 lantic has a more northward course in mid-ocean than that of 

 the Pacific. It consequently bears up the isocryme of 35° F. 

 to the parallel of 50°, that is, six degrees above the mean. 

 The effect on the other isocrymes of the Atlantic is very re- 

 markable. We perceive, in the first place, that the most 

 southern point of each of these isocrymes is not far from the 

 mean position of the same isocrymes in the Pacific, while the 

 most northern point of each is ten to twenty-five degrees 

 further north. Taking the position of the isocrymes of 68° 

 and 74° F., where they cross the meridian of 15° west, as the 

 mean position for this ocean, we find that the former is eight 

 degrees in latitude farther north than 68° F. in the South 

 Pacific ; and the mean for the latter is in 7° south, while for 

 the same in the Pacific it is 20° south, making a difference 

 of thirteen degrees. The effect of the cold southern waters 

 is consequently not along the African coast alone, but per- 

 vades the whole ocean. It is hence obvious, how utterly 

 untenable the common notion that the tropical current from 

 the Indian Ocean is the same which flows up the west Afri- 

 can coast. With a temperature of 56° south of Cape Town, 

 it would be wholly incapable of causing the great deflections 

 for the whole South Atlantic which have been pointed out. 

 It combines with the cold current, but does not constitute it. 

 The facts thus sustain the opinions long since brought for- 

 ward by the distinguished meteorologist Mr Wm. C. Red- 

 field, that the currents flowing north along the African and 



