DEEP SEA FAUNA 1305 



of the Protozoa rhizopods, sponges, or both pre r 

 dominated greatly over all other forms of animal 

 life in the depths of the warmer regions of the sea. 

 The rhizopods, like the corals of a shallower zone, 

 form huge accumulations of carbonate of lime, and it 

 is probably to their agency that we must refer most 

 of those great bands of limestone which have resisted 

 time and change, and come in here and there with 

 their rich imbedded lettering to mark like milestones 

 the progress of the passing ages. 



We find the first and simplest of the invertebrate 

 sub-kingdoms, the Protozoa, represented by three 

 of its classes the monera, the rhizopoda, and the 

 sponges. The monera have been defined as a distinct 

 class by Professor Ernst Haeckel, of 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. The monera pass into the rhizopoda, 

 which give a slight indication of advance in the defi- 

 nite form of the graceful, calcareous, shell-like 

 structures which most of them secrete, and the two 

 groups may be taken* together. 



The dredging at 2,435 fathoms at the mouth of 

 the Bay of Biscay gave a very fair idea of the con- 

 dition of the bottom of the sea over an enormous 

 area, as we know from many observations which 

 have now been made with the various sounding 

 instruments contrived to bring up a sample of the 

 bottom. Under the microscope the surface-layer 

 was found to consist chiefly of entire shells of 

 Globigerina bulloides, large and small, and frag- 



