SURFACE-SWIMMING FAUNA (INVERTEBRATES). 101 



they could see them better, prey upon them, so 

 long as there are Fish in the sea to provide a 

 more substantial and satisfactory meal. The 

 Whales, as they dash through the water with 

 their huge mouths wide open, undoubtedly 

 swallow them in thousands, but it can not be 

 reasonably supposed that the Whale can be 



fuided by sight in the selection of its food. 

 A T e ought not, perhaps, to go so far as to 

 say that it is no protection to them, for Prof. 

 Moseley states that the Turtle sometimes feeds 

 upon the Yelellas, but at the same time we may 

 consider that the transparency is an effect pro- 

 duced by the large amount of water in their 

 tissues, which is there for the purpose of re- 

 ducing their specific 

 gravity and assisting 

 in that manner in their 

 floatation. 



The only Gastropod 

 found in the open seas 

 which retains in its 

 characteristic form the 

 large coiled shell, is 

 the beautiful blue 

 Janthina, famous for 

 its habit of construct- 

 ing a little raft which 

 floats on the surface 

 of the sea. To the 

 underside of this it attaches its eggs and spends 

 its life in pushing or dragging the raft about. 



No account of the Molluscs of the Plankton 

 would be complete without some reference to 



FIG. 28. 



rteropod, show'ng the so-called 

 \vings, 



