CRUSTACEA OF THE DEEP SEA 133 



had been supposed to be barren of all life, it was 

 confidently expected that representatives would be 

 discovered of some of the 

 animals known as fossils 

 from the earlier geological 

 periods. It was believed 

 that the great ocean basins 

 had remained unchanged 

 for vast periods of geologi- 

 cal time, and that numer- 

 ous "living fossils" would 

 be found surviving in the 

 depths. These hopes have 

 not been fully realized, for 

 the deep-sea fauna as a 

 whole has proved to be of 

 a comparatively modern 

 type ; nevertheless, it does 

 include a considerable 

 number of primitive and 

 old-fashioned forms of life, 

 some of which belong to 

 groups elsewhere extinct. 

 This is conspicuously the 



FIG. 46 Polycheles phosphorus, 



case among the Crustacea. ONE OF THE ERYONIDEA, 



The lobster-like FrvoniHea FEM ALE, FROM THE INDIAN 



a ' SEAS. (From British Museum 



which at the present day Guide, after Alcock.) 



are only found in the deep sea, were long known as 



fossils before they were discovered to survive as living 



