48 THE PROBLEMS OF THE DEEP SEA n 



Milne Edwards carried out the principle of distin- 

 guishing the Faunae of different zones of depth 

 much more minutely, in their " Recherches pour 

 servir a 1'Histoire Naturelle du Littoral de la 

 France," published in 1832. 



They divide the area included between high- 

 water-mark and lowwater-mark of spring tides 

 (which is very extensive, on account of the great 

 rise and fall of the tide on the Normandy coast 

 about St. Malo, where their observations were 

 made) into four zones, each characterized by its 

 peculiar invertebrate inhabitants. Beyond the 

 fourth region they distinguish a fifth, which is 

 never uncovered, and is inhabited by oysters, 

 scallops, and large starfishes and other animals. 

 Beyond this they seem to think that animal life 

 is absent. 1 



Audouin and Milne Edwards were the first to 

 see the importance of the bearing of a knowledge 

 of the manner in which marine animals are 

 distributed in depth, on geology. They suggest 

 that, by this means, it will be possible to judge 

 whether a fossiliferous stratum was formed upon 

 the shore of an ancient sea, and even to determine 

 whether it was deposited in shallower or deeper 

 water on that shore ; the association of shells of 

 animals which live in different zones of depth will 



1 " Enfin plus bas encore, c'est-a-dire alors loin des cotes, le 

 fond .des eaux ne parait plus etre habite, du moins dans nos 

 mers, par aucun de ces animaux" (1. c. torn. i. p. 237). The 

 " ces animaux " leaves the meaning of the authors doubtful. 



