408 THE DEPTHS OF THE SEA. [chap. ix. 



The remarkable general result that even to these 

 great depths the fauna is varied and rich in all the 

 marine invertebrate groups, has inundated us with 

 new material which in several of the larger depart- 

 ments it will take years of the labour of specialists 

 to work up. While referring very briefly to those 

 orders which it has been found impossible as yet to 

 overtake, I will enter a little more fully into the 

 history of certain restricted groups which more par- 

 ticularly illustrate the conditions of the abyssal 

 region, and the relations of its special fauna to the 

 faunae of other zoological provinces, or to those of 

 earlier times. And very prominent among these 

 special groups we find the first and simplest of the in- 

 vertebrate sub-kingdoms, the Protozoa, represented 

 by three of its classes, — the monera, the rhizopoda, 

 and the sponges. 



The monera have been lately defined as a distinct 

 class by Professor Ernst Haeckel,^ for a vast assem- 

 blage of almost formless beings, apparently abso- 

 lutely devoid of internal structure, and consisting 

 simply of living and moving expansions of jelly-like 

 protoplasm ; and although the special character on 

 which Haeckel separates them from the remainder of 

 the protozoa, — that they are propagated by no form 

 of sexual reproduction, but simply by spontaneous 

 division, — may probably prove deceptive as our know- 

 ledge increases, still their number, their general 

 resemblance to one another, presenting obviously 

 different and recognizable kinds although with very 

 indefinable characters, and the important part Avhich 



^ Biologische Sludien. Von Dr. Ernst Haeckel, Professor an der 

 Universitat Jena. Leipzig, 1870. 



