306 REPORT OF NATIONAL MUSEUM, 1892. 



While ;i greater or less number of other kinds of animals, such as the 

 Cetacea, Sirenia, birds, reptiles, etc., resort to or live in marine waters, 

 only invertebrates and fishes have marine aqueous respiration. It is 

 therefore evident that with the foreinentioned exceptions, together with 

 that of their ancient representatives, these kinds of animals only have 

 ever been denizens of marine waters, and it is also evident that with 

 the exception of a few migratory kinds the remains of denizens of 

 marine waters found intombment in no other than marine sedimentary 

 deposits. 



The character of the physiological functions of all the other animals 

 which are represented by fossil remains made them denizens either of 

 the land or of nonmarine waters. In view of this fact and of others 

 which have been mentioned in Essay i, b is apparent that with few 

 and mostly accidental exceptions their remains became fossilized only 

 in nonmarine sedimentary deposits. 



The land in the vicinity of inland bodies of water naturally consti- 

 tuted a more congenial habitat for such plants as have in part become 

 fossilized than did open seacoasts, and, as shown in Essay I, plant re- 

 mains were nmch more likely to have become preserved in nonmarine 

 than in marine sediments. This statement is supported by the fact that, 

 with rare exceptions, all discovered plant remains, especially such as are 

 preserved in a classifiable condition, are found in nonmarine deposits, 

 which an? shown to be such by the character of the accompanying re- 

 mains of aquatic faunas. Among the apparent exceptions to this rule 

 are the beds of coal, and of shale containing plant remains, which are 

 found to alternate with other beds bearing remains of unmistakably 

 marine animals. These cases, however, are regarded as representing 

 alternate subsidence and slight emergence of marshy land with relation 

 to the level of shallow marine waters. Such conditions are accordant 

 with the foreinentioned alternation of the remains of land plants with 

 those of marine animals, and also with the fact that the actual com- 

 mingling in one and the same bed of the two kinds of remains has very 

 rarely been discovered. 



The foregoing facts make it evident that as a rule, having only the 

 exceptions just indicated, strata of marine origin contain no other fos- 

 sil remains than those of invertebrates and fishes. It should also be 

 remarked in this connection that fish remains are often absent from 

 strata that contain invertebrate remains in great abundance, ami that 

 in all other cases the proportion of the former to the latter is very small 

 as regards both numbers and variety — that is, as a rule, fish remains 

 are comparatively so rare that a large proportion of the marine forma- 

 tions are found to contain no other fossil remains than those of inver- 

 tebrates. Those facts also make it evident that with few and compar- 

 atively unimportant exceptions the remains of all land animals, as well 

 as those of all land plants, are found only in sedimentary deposits of 

 nonmarine origin. 



