— i5 — 



purely local origin. Hence there are no abyssal crinoids in these 

 seas, as none have been able to enter. The reason for the 

 absence of Pacific abyssal water is that the water of the deeper 

 portions all enters these basins originally in the form of the 

 Tsu-Shima current through the Straits of Korea, and the Tsu- 

 shima current fills the Korean Straits to the bottom. No Pacific 

 abyssal water can enter through any of the very few other 

 available channels for the reason that it cannot force itself 

 against the pressure in these seas, arising from the great 

 volume of water which enters the Korean Straits, a pressure 

 which is sufficent to raise the surface both of the Sea of Japan 

 and the Sea of Okhotsk slightly above that of the Pacific 

 in the same latitudes. 



Of course in the Sea of Japan, the Sea of Okhotsk and the 

 Bering Sea the rotation of the earth acts to turn the currents 

 entering from the south toward the east, so that they keep as 

 closely as possible to the eastern shores ; but off the western 

 coast of South America south of the equator the same force 

 operates to turn the northward flowing currents to the left, 

 away from the coast. As already explained, however, the 

 Humbolt current continues in a northerly direction through 

 the latitudes where this effect is greatest, and succeeds in 

 reaching the Central American coast, where, and beyond 

 which, the influence of the rotation of the earth is to cause it 

 to keep as closely as possible to the coast, as in the case of 

 the northward flowing currents in the three enclosed seas. 



There is, so far as we can see, no marked difference in 

 temperature or in salinity between the Humbolt current, the 

 antarctic water, and the abyssal water of the Pacific ; they are 

 in all probability the same, together forming a single unit 

 of which we are accustomed to differentiate the southern and 

 southeastern portions as currents simply because they are 

 in rapid motion, and reach the surface, exactly as we differen- 

 tiate the currents along the southern and eastern shores of 

 the Sea of Japan and of the Sea of Okhotsk from the abyssal 

 waters of those seas, of which they are in reality an integral 

 part. 



(285) 



