. PROFESSOR HUXLEY'S LECTURES. 211 



direct support to the doctrine of evolution, but they are perfectly- 

 capable of being interpreted in consistency with it. There is another 

 order of facts of the same kind, and susceptible of the same interpre- 

 tation. The great group of Lizards, which abound so much at the 

 present day, extends through the whole series of formations as far 

 back as what is called the Permian epoch, which is represented by 

 the strata lying just above the coal. These Permian lizards differ 

 astonishingly little from the lizards which exist at the present day. 

 Comparing the amount of difference between these Permian lizards 

 and the lizards of the present day with the prodigious lapse of time 

 between the Permian epoch and the present age, it may be said that 

 there has been no appreciable change. 



But when you carry your researches farther back in time you find 

 no trace whatever of lizards nor of any true reptile whatever in the 

 whole mass of formations beneath the Permian. Now, it is perfectly 

 clear that if our existing paleontological collections, our existing 

 species of stratified rock, exhaust the whole series of events which 

 have ever taken place upon the surface of the globe, such a fact as 

 this directly contravenes the whole theory of evolution, because this 

 theory postulates that the existence of every form must have been 

 preceded by that of some form comparatively little different from it. 

 Here, however, we have to take into consideration that important fact 

 so well insisted upon by Lyell and Darwin the imperfection of the 

 geological record. It can be demonstrated as a matter of fact that 

 the geological record must be incomplete, that it can only preserve 

 remains found in certain favorable localities and under particular 

 conditions ; that it must be destroyed by processes of denudation, 

 and obliterated by processes of metamorphosis by which I mean 

 that beds of rock of any thickness crammed full of organic remains 

 may yet, either by the percolation of water through them or the in- 

 fluence of subterranean heat (if they descend far enough toward the 

 centre of the earth), lose all trace of these remains, and present the 

 appearance of beds of rock formed under conditions in which there 

 was no trace of living forms. Such metamorphic rocks occur in for- 

 mations of all ages, and we know with perfect certainty when they 

 do appear that they have contained organic remains, and that those 

 remains have been absolutely obliterated. 



I insist upon the defects of the geological record the more be- 

 cause those who have not attended to these matters are apt to say to 

 us, "It is all very well, but, when you get into difficulty with your 

 theory of evolution, you appeal to the incompleteness and the imper- 

 fection of the geological record ; " and I want to make it perfectly 

 clear to you that that imperfection is a vast fact which must be 

 taken into account in all our speculations, or we shall constantly be 

 going wrong. 



You will all see that singular series of tracks which is copied of 



