PELAGIC ANIMAL LIFE 



653 



Arctic, the boreal, and the subtropical Atlantic forms are met 

 with in succession, their distribution changing according to 

 seasons and local conditions ; the boreal waters are here 

 squeezed between bodies of Arctic and Atlantic water, and the 

 transitions between the different bodies of water and between 

 the different animal-communities are very sudden. 



"Ipii 



Fig. 486 — Skin of Cachalot with marks from struggle with Architeuthis. 



Nat. size. 



The tow-nettings made by the "Michael Sars " in 1910 

 between the Sargasso Sea and Newfoundland and thence 'to 

 Ireland are particularly interesting, because they comprise 

 Arctic, boreal, and Atlantic forms mingled together in the same 

 oceanic area, and afford a rare opportunity for observing to 

 what extent the distribution of different forms depends jon 

 certain physical conditions. 



