— i8 — 



are much greater than those at any point in the territory 

 inhabited by the genus, except off southern California. 



It seems reasonable to suppose that there is here some 

 factor which operates to (i) raise the antarctic water, with the* 

 crinoids which live in it, considerably above the depth at which 

 it normally occurs, and (2) to mix it with warmer water. 



The pocket-like Gulf of Alaska undoubtedly acts as a bar- 

 rier to the cold antarctic water which, also impelled to turn to 

 the right (east) through the here strong action of the earth's 

 rotation, on the coast of Alaska and as far south as Washington, 

 is thus driven up near or to the surface. 



The surface w T ater of the Kuro-Siwo, driven into this 

 region by the strong westerly winds, at first maintains more 

 or less unaltered its original integrity ; but the southern branch 

 gradually becomes more and more mixed with the antarctic 

 water over which it flows, this mixing being greatly facilitated 

 by the fact that the two are of the same salinity so that 

 no distinct plane of separation or division can be main- 

 tained between them. Consequently this southerly current, 

 derived originally from surface drift from the Kuro-Siwo, 

 as it progresses becomes colder and colder, and exhibits the 

 apparent anomaly of a current becoming colder as it proceeds 

 southward, so that when it reaches the California coast it has 

 become a cold current the water of which is derived (1) from 

 the easterly drift of the Kuro-Siwo, plus (2) an ever increasing 

 amount of antarctic water dissolved, so to speak, by it, and 

 carried backward over the course it travelled a short time 

 before. 



This is the only possible explanation of the cooling of this 

 current as it proceeds from north to south which accords with 

 the distribution of the antarctic organisms in the region. 



Our knowledge of the northerly derivative from the drift of 

 the Kuro-Siwo, which enters the Gulf of Alaska and turns 

 westward, running along the Aleutian Islands, is too limited 

 to permit us to say much about it ; but so far as we can see 

 the same phenomena occur as in the case of the southern 

 derivative. 



