The great role played by water currents in the dispersal of marine animals has long been recognized and put to use in the explanation of animal distribution both planktonic and benthic. Conversely the pelagic animals may in some instances be very useful as indicators of the source or nature of the water movements. Many years ago, Cleve (1900) recognized this fact in his investigations of passively floating life but failed to fully distinguish between geographic and biological groups (Gran 1902). evertheless the principle of his hypothesis is good as expressed by Cleve-Eulser (1928) in the following: "regular biological analysis of the oceans and of the coastal waters would no doubt give a more thorough knowledge of the sea currents, their movements and their intermingling, than could be expected from hydrographic observations only."