NORTH PACIFIC OPHIURANS IN NATIONAL MUSEUM CLARK. 



13 



ern channel of the Straits of Korea five other Honshu species appear, 

 while even Ophiura sarsii is now no longer to be found. Returning 

 to the east coast of Honshu Island, we find that the Albatross did 

 very little collecting north of Sagami Bay, and that little was 

 done in the vicinity of Kinkaasan Light, just above the thirty- 

 eighth parallel. In that region the Oceanic and Bering faunas 

 are each represented by two species and the Honshu fauna by one. 

 In Sagami Bay, the abundant ophiuran fauna is almost exclusively 

 Honshu. It appears, therefore, quite clear that the thirty-sixth 

 parallel approximately indicates the line of separation between the 

 Bering and Honshu faunas both in the Sea of Japan and on the 

 Pacific coast. So far as the latter is concerned the reason seems 

 obvious, for it is in this region that Honshu Island bends abruptly 

 northward and the great, warm Kuroshiwo current from the south, on 

 its Pacific side, meets and deflects the cold current from Bering Sea. 

 It is less easy to see why in the Sea of Japan the two faunas should 

 meet along the same parallel, but it is probable that the fauna of that 

 sea has been formed by the entrance of northern species through La 

 Perouse Strait and of southern species through the Straits of Korea. 

 The local conditions appear to be more favorable to the northern 

 species in that greater part of the sea which lies above the thirty-sixth 

 parallel. 



BATHYMETRICAL AND TEMPERATURE DISTRIBUTION. 



No less interesting than the geographical distribution is the dis- 

 tribution with reference to depth and temperature. Seven species 

 were taken only in water exceeding 1 ,000 fathoms. They are : 



While all are probably abyssal species, so few stations (six) are 

 represented we have almost no light on their real bathymetrical dis- 

 tribution. In view of the bathymetrical range of 965 fathoms 

 (1,008-1,973), the extraordinarily limited temperature range of less 

 than two degrees (36.8-34.9) is the most interesting point about 

 this group of species, but it would have more significance were more 

 stations involved . 



