EVIDENCE FROM PALAEONTOLOGY 85 



the paucity of fossils is all the more evident. It 

 needs no argument to prove that in this case the 

 record is lamentably incomplete and it is typical of a 

 great many others. In a sense, the foot-prints them- 

 selves constitute a record, but it is one that we do 

 not know how to decipher. 



On the other hand, matters have greatly improved 

 since Darwin wrote his oft-cited Chapter X; many 

 lands then geologically unknown have been explored 

 and many of the missing chapters and paragraphs in 

 the history of life have been brought to light. The 

 most ancient biologically intelligible period of the 

 earth's history is called the Cambrian and, compared 

 with the succeeding periods, the Cambrian has al- 

 ways been poor in fossils, great areas and thicknesses 

 of rocks being entirely barren. No one could doubt 

 that our knowledge of Cambrian life was most in- 

 complete and inadequate. A few years ago Dr. C. D. 

 Walcott, Secretary of the Smithsonian Institution, 

 discovered in the Canadian Rockies a most marvel- 

 lous series of Cambrian fossils of an incredible del- 

 icacy and beauty of preservation, which have thrown 

 a flood of new and unexpected light into very dark 

 places. It is clear that the Cambrian seas swarmed 

 with a great variety and profusion of life, but that in 

 only a few places, so far known to us, were the condi- 

 tions such that these delicate creatures could be 

 preserved. It is not possible to say how far the 

 difficulty caused by the imperfection of the geological 

 record will be removed by the progress of discovery. 



