34 IOWA GEOLOGICAL SURVEY 



fishes, to survey the larger aspects of palaeontology and to set 

 forth something of its general aim and scope. And first it is 

 to be noted that the study of extinct animal organisms, that is, 

 palaeozoology, is merely an extension of zoological science, just 

 as the study of fossil plants is an extension of botanical science. 

 The former of these is, in fact, merely the rehabilitated zoology 

 of the past, as the latter is merely the rehabilitated botany. 

 The true aim of palaeontology is to restore to us visions of van- 

 ished life-periods ; to unfold to our view the ceaseless procession 

 of animate forms that, slowly transforming, very gradually pro- 

 gressing, sometimes retrograding, keeps up its steady file 

 through the ages from twilight antiquity down to our own day. 

 Figuratively speaking, this science realizes the dream of the 

 ancient poets who described certain gifted mortals as having 

 been privileged to descend into the interior of the earth, and, 

 after their return to the upper air, amazing their fellows with 

 tales of the wonders thus revealed. Only, in the present case, 

 the wonders are not imaginary but real, and we are permitted to 

 behold through the windows which palaeontology opens up for us 

 amid stratifications and ruins, not only a manifold of shifting 

 phenomena, but anon the glint and shimmer of the wheels, as it 

 were, of the controlling mechanism. Science shows us these 

 manifestations, philosphy teaches us to think of them in terms of 

 cause and effect, and to sift out from them certain ultimate con- 

 ceptions. 



If the mind of the astronomer wearies in the effort to con- 

 template an infinity of space, so the palaeontologist is over- 

 whelmed by the sweep of the universe through endless time. In 

 his domain a sense of the time-element is ever-present and all- 

 pervading. He acquires the habit of contemplating all things 

 sub specie aeternitatis. He is concerned with fixing the order 

 and character of events throughout all past time in all places. 

 By virtue of the time-element entering into it, palaeontology 

 becomes at bottom an historical science, and the underlying 

 attitude of the inquirer is, therefore, on a parity with that of 

 the historian of human events. It is well not to lose sight of 

 this fact. 



