EVOLUTION IN THE DEEP SEAS 237 



fore to be expected that the process of evolution will differ in its 

 details, if not in its more fundamental characters, when unlike 

 environments are compared. There is always a tendency in dis- 

 cussion of a broad subject such as evolution to lay the emphasis 

 on the more accessible parts of the subject and to disregard other 

 parts which cannot be investigated so easily. This is certainly true 

 of the study of evolution, for by far the greater part of the modern 

 theories of evolution has been founded on observation and experi- 

 ment in terrestrial environments. It therefore seemed worth while 

 to point out that the modern scheme need not necessarily apply 

 in its details to all environments. The deep sea and the land, being 

 environments as different as any to be found in the world today, 

 seemed well adapted to establish these points by a comparison of 

 the process of evolution in them, 



REFERENCES 



Ekman, S. 1953. Zoogeography of the Sea. Sidgwick and Jackson, London. 

 Marshall, N. B. 1954. Aspects of Deep-Sea Biology. Hutchinson, London. 

 Menzies, R. J., and J. Imbrie. 1958. On the antiquity of the deep-sea bot- 

 tom fauna. Oikos, 9, 192-209. 

 Wright, S. 1943. Isolation by distance. Genetics, 28, 114-138. 

 Zeuner, F. E. 1946. Dating the Past. Methuen, London. 



