i] THE CATEGORIES OF LIFE 5 



This mud would form in the deeper depressions where 

 the run of tide is weakest, and we should never find 

 it on ridges of rock standing up from the sea bottom. 

 Now all these materials come from the wasting away 

 of the land, but we should also find sea-bottom deposits 

 which are formed by the agencies of living creatures. 

 There would be patches of hard, sandy substance 

 formed by the tubes of the worm Sabellaria; here 

 and there deposits of the coral-like skeletons of 

 calcareous algae, or Corallines; and perhaps also 

 extensive deposits of broken shell fragments. So 

 far we should have got down to a depth of perhaps 

 50 fathoms. 



The life inhabiting the sea-bottom would not differ 

 much from that which we had already observed in 

 the Laminarian zone, but there would of course be 

 greater variety, especially in regard to the fishes. 

 The latter would consist of plaice, dabs, soles, gur- 

 nards, skate and ray, codling, whiting, dogfishes, and 

 others. There would be shrimps on the shallower 

 sandy bottoms, accompanied by hosts of invertebrates 

 such as various species of crabs, starfishes, ophiurids, 

 sea-urchins, hermit-crabs, polyzoa and many others. 

 In the deeper places near the 20-fathom line there 

 would be other species of fishes not found in the 

 shallower water, such as turbot and brill, and there 

 would also be a difference in the invertebrates : the 

 larger squids and cuttle-fishes and many others would 



