140 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



otherwise co-extensive with the area over which the 

 operations are conducted. It is a well-known fact that 

 land animals and plants have a distribution which depends 

 largely on the physical conditions of their surroundings. 

 One is apt to forget, however, that the same holds good 

 regarding marine life. The sea may appear limitless in 

 extent, but, after all, there are many animals and plants 

 in it that are just as nicely adjusted to their habitat as 

 their relations on land, and any change that takes place 

 in their surroundings has some effect, one way or another, 

 on the inhabitants of the sea. We know far more 

 regarding the inhabitants of the land solely because of the 

 comparative ease in reaching them, compared with the 

 difficulties that lie before the marine investigator. The 

 worker amongst land animals and plants can now afford 

 time to deal with variation in structure, &c, but the 

 marine student has not, by any means, exhausted the vast 

 storehouse of the deep of all its novelties. It is only 

 within comparatively recent years that a wide-spread 

 study of marine life has been undertaken. The 

 co-operation of the Governments of various countries and 

 Sea-Fisheries Authorities, along with the efforts put forth 

 by independent naturalists, has done much to stimulate 

 marine research. The result is, we know a great deal 

 more regarding the distribution of certain classes of 

 pelagic and semi-pelagic organisms now than we did a few 

 years ago. Every scientific expedition throws fresh light 

 on the subject. There are still quite a number of 

 organisms whose present distribution is very limited, but 

 whether they will prove on further investigation to be so 

 local is doubtful. Many new forms of Copepoda were 

 brought to light by the investigations conducted on the 

 " Challenger " over thirty years ago. Some of them 

 were found in tropical seas, and might have been looked 



