84 New York State Museum 



are most generally distributed, and there is a diversity of 

 form ; crustaceans are abundant, mostly blind and spinous 

 forms ; silicious sponges are present, often very abundant, 

 especially nearer land ; all the principal groups of the 

 mollusks are represented except pelagic forms ; there are 

 a few brachiopods ; among the coelenterates a large pro- 

 portion of the species is restricted to deep waters, this 

 being the only group, however, of which this is true; 

 almost all of the fishes are of the bony or teleostean type, 

 the true fishes. Just as in the shallow waters, the deep- 

 sea animals, especially echinoderms, sponges etc., have a 

 tendency to live together in colonies with various other 

 animals associated with them. It must be remembered, 

 however, that life is not abundant in the great deeps. 

 Studies of marine life have shown that the animals of 

 the deeps are not old in a geological sense. None of the 

 creatures of the deep-sea dates back beyond Mesozoic 

 times, but the present shallow seas show 25-35 genera 

 and some species that go back to the Paleozoic. 



Below the deeps the sea bottom is covered with fine 

 muds and oozes. The stillness of the water and the in- 

 creasing pressure cause the deposition of the very 

 finest muds. Beyond these muds, which are the finest 

 materials washed out from the shores, are the various 

 oozes composed of the shells of millions upon millions of 

 the small creatures that die in the layers above. One of 

 the most common oozes is the Globigerina ooze. This 

 consists of the minute shells of Foraminifera, mostly 

 species of Globigerina, together with some of the bottom 

 living forms, etc. Then there are the less common radio- 

 larian oozes, diatom oozes and the pteropod oozes com- 

 posed of shells of oceanic mollusks. When one reaches 

 the middle of the oceans the character of the bottom 



