PEEFACE XI 



to select a few only of those which bear most directly 

 upon the points at issue. 



To overburden my work with the names of genera 

 or the lists of species would not, it seemed to me, 

 either clear the issues or interest the general reader. 

 These may be found in the ' Challenger ' monographs, 

 and other books dealing with the subject. 



Those who wish to pursue the subject further will 

 find in the ' Voyages of the " Blake," ' by Alexander 

 Agassiz, an excellent and elaborate discussion of 

 deep-sea problems, and numerous illustrations of some 

 of the most interesting forms of abysmal life. 



In Volume XXIII. of the ' Bulletin of Compara- 

 tive Zoology ? the same author gives a most interest- 

 ing account of the deep-sea work that has recently 

 been done by the ' Albatross ' expedition. 



Filhol's ' La Vie au Fond des Mers ' is also a book 

 that contains a great deal of new and interesting 

 matter, together with some excellent coloured plates 

 of deep-sea animals. 



SYDNEY J. HICKSON. 



DOWNING COLLEGE, CAMBRIDGE : 

 September, 1893. 



