Handbook of Paleontology 85 



changes again. The oozes give place to an excessively 

 fine, red mud characteristic of all the abysses far from 

 land. In this mud, as also sometimes in the oozes, have 

 been found in scattered distribution the ear bones of 

 whales and the teeth of sharks, some of which are of 

 great size, several inches in length, and belong to extinct 

 species which have been found elsewhere in the fossil 

 state. 



It is not to the abysses but to the shallower waters 

 bordering the coast that one must go to find conditions 

 similar to those under which most of our geologic forma- 

 tions were deposited, and it is in such areas that one will 

 find life similar to that represented by the fossils in our 

 rocks. , 



Geographical Range 



The fact that animals have a geographical distribution 

 has been touched upon above, and it has been shown that 

 this factor enters little into a consideration of the deeper 

 waters because of uniformity of conditions below a cer- 

 tain depth. In general, all living things in the sea have 

 their appointed boundaries ; certain types of situations 

 always have the same groupings of animals and plants 

 which are known as associations. We have animal asso- 

 ciations, plant associations, and plant and animal associa- 

 tions. Each type of beach has a life peculiar to itself. 

 The types of animals that are found on a rocky shore, 

 stony or sandy beaches, or mud flats in one place will be 

 found under similar physical conditions in other places. 

 This is subject, of course, to modification by climatic 

 conditions and over wide ranges there will be a differ- 

 ence in genera and species. For instance, certain sea 

 urchins and starfishes are characteristic of the rocky 

 shores of Maine, other forms inhabit the rocky shores of 



