ON THE FAUNA OP JAPAN. 123 



mrmritiana. Molluscs oftentimes ir.et ^Yitll are Snccifteo ogasawcrj'ae, 

 EuJota ■Eiom'Ioris, and Opeas pyrgula. 



Marine Fauna. 



When we turn to coDsider tlie marine fauna of the Japanese 

 waters w^e find that all of the zoologists who ha^'C worked out on it 

 are inclined to think that our luarine animals are closely related not 

 onl}^ to a part of the Indo-Pacific I'egion but also to that of the 

 Behring Sea. The main factor which affects this state of animal life 

 is that due to tlie ])hysicai conditions of the sea. Setting aside the 

 daily and seasonal changes, and those, which rarely happen, by vol- 

 canic agency, we find a great factor in the temperature of the water 

 as well as in the motion of the oceanic currents. As thermal regulators 

 of the water are first of all to be taken into account the oceanic 

 currents. We may here take a glance at the currents ai'ound tlie 

 Japanese islands. 



On the Pacific side we have two principal streams of different 

 temperatures. The warm current is known as the Japan stream, or 

 Kuro-shiwo, which is peculiar for its high salinity. This stream has 

 its origin in the north Pacific current from the east, and passes 

 into the East China Sea, moving northwards by way of Luzon and 

 Formosa. Near the south cape of Formosa it sends off a branch, which 

 runs towards the I'ormosan channel, along the western coast of the 

 island, and merges finally into the main stream. After flowing out to 

 the Pacific chiefly by the pass between Yakushima and Amami-Oshi- 

 nia, the stream moves in an east-north-easterly direction towards the 

 Shiwo-no-misaki where it comes very close to the shore, and then 

 turns more to the east. In its course the stream floods the bays of 

 Kagoshima, Tosa, Suruga, Sagami, and others. After travelling along 

 the coast of the Boso peninsula, the current debouches into the open 

 sea between 30° and 50^ N. lat., and passes in part northwards to the 

 Aleutian islands. 



The cold ciuTcnt is the well-known Kamchatka stream, or O^'a- 

 shiwo, which rises from tlie Behring Sea, and passes down south along 

 the eastern coast of the Kurile group and Hokkaido, extending farther 

 southwards off Kinkwasan, or beyond, where it meets the aforesaid 

 Kuro-shiwo. Both streams vary in strength at different seasons ; the 

 Kuro-shiwo is stron^rest in the warmer season and weakest in the 



