Z BIOLOGICAL SOCIETY OF WASHINGTON. 



which we have been wont to act, and to inquire whether they 

 will bear the light of rapidly increasing knowledge. I propose 

 to-night not only to point out the insufficiency of the evidence 

 which is relied upon to support some of the assumptions of 

 paleontology, but to challenge the truth of some of the proposi 

 tions which its leading men have been in the habit of treating as 

 fixed laws of unquestionable and universal application, and to 

 show that they are not in harmony with the facts of philosophical 

 biology. I comprehend the danger that those who are not 

 familiar with the leading principles of paleontology, hearing only 

 a statement of the misconceptions which its votaries have fallen 

 into, will be inclined to underestimate its fundamental truths, 

 which are really unassailable. I wish to say, therefore, that I 

 have no intention of treating my subject wantonly ; and I shall 

 be sorry to weaken the faith of any one in the general truths of 

 a, science which has done more than any other to broaden the 

 minds of men as to the problems of animal and vegetable life ; 

 and which has a future before it, the brilliance of which is in no 

 danger of being obscured. 



The remarks which I am about to make refer mainly to certain 

 errors, not yet entirely eliminated, which early obtained a foot 

 hold in paleontology, as a natural consequence of the biological 

 opinions then prevailing, and which were inseparable from its 

 stage of transition and growth. Modern paleontology, like the 

 other sciences, has been a matter of growth ; and errors once 

 introduced have been found difficult to eradicate, even after an 

 increase of knowledge has shown them to be such ; and it is 

 an unpleasant fact that our science, as it is now taught and 

 practised, even by some of the best authors, is marred by some 

 of its early defects. 



The first and principal question which I propose to discuss 

 relates to the chronological order of succession of animal and 

 vegetable types, and their geographical distribution during their 

 existence. 



